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+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt striking across it, symbolizing global communication.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.110**
+
+(07/96)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Mobile service – Mobile services and multdestination  
+satellite services
+
+---
+
+**Operational provision for the maritime mobile  
+service**
+
+ITU-T Recommendation F.110
+
+(Previously “CCITT Recommendation”)
+
+---
+
+# FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation F.110 was revised by ITU-T Study Group 1 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of July 1996.
+
+---
+
+# NOTE
+
+In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+© ITU 1996
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU.
+
+# CONTENTS
+
+|                                                                                                                                                | <i>Page</i> |
+|------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| DIVISION A – GENERAL.....                                                                                                                      | 1           |
+| 1 Scope.....                                                                                                                                   | 1           |
+| 2 References.....                                                                                                                              | 1           |
+| 3 Definitions.....                                                                                                                             | 2           |
+| 4 Order of priority .....                                                                                                                      | 2           |
+| 5 Limitations .....                                                                                                                            | 3           |
+| 6 Service hours .....                                                                                                                          | 3           |
+| DIVISION B – RADIOTELEGRAMS .....                                                                                                              | 4           |
+| 1 Preparation and handing-in of radiotelegrams .....                                                                                           | 4           |
+| 1.1 Indication of station of origin .....                                                                                                      | 4           |
+| 1.2 Use of accounting authority identification codes by mobile stations .....                                                                  | 4           |
+| 1.3 Time of handing-in .....                                                                                                                   | 4           |
+| 1.4 Address .....                                                                                                                              | 4           |
+| 2 Counting of words.....                                                                                                                       | 5           |
+| 3 Routing of radiotelegrams.....                                                                                                               | 5           |
+| 4 Transmission of radiotelegrams .....                                                                                                         | 5           |
+| 4.1 Routine repetition .....                                                                                                                   | 5           |
+| 4.2 Doubtful reception .....                                                                                                                   | 6           |
+| 4.3 Long distance radiocommunications .....                                                                                                    | 6           |
+| 4.4 Routine retransmission by mobile stations .....                                                                                            | 7           |
+| 4.5 Period of retention of radiotelegrams at land stations.....                                                                                | 7           |
+| 5 Advice of non-delivery .....                                                                                                                 | 8           |
+| 6 Radiomarine letters .....                                                                                                                    | 8           |
+| 7 Special services .....                                                                                                                       | 8           |
+| 8 Special conditions relating to the maritime mobile-satellite service.....                                                                    | 8           |
+| DIVISION C – RADIOTELEX .....                                                                                                                  | 9           |
+| 1 General.....                                                                                                                                 | 9           |
+| 1.1 Routing of calls.....                                                                                                                      | 9           |
+| 1.2 Information to be supplied, as necessary by the calling party .....                                                                        | 9           |
+| 1.3 Call duration .....                                                                                                                        | 9           |
+| 1.4 Validity of requests.....                                                                                                                  | 10          |
+| 1.5 Exchange of radiotelegrams by radiotelex.....                                                                                              | 10          |
+| 2 Traffic from mobile stations to subscribers of the international telex service .....                                                         | 10          |
+| 2.1 Automatic operation .....                                                                                                                  | 10          |
+| 2.2 Single-operator operation .....                                                                                                            | 10          |
+| 2.3 Semi-automatic operation .....                                                                                                             | 10          |
+| 2.4 Manual operation.....                                                                                                                      | 10          |
+| 2.5 Store-and-forward service .....                                                                                                            | 10          |
+| 2.6 Operational procedures.....                                                                                                                | 11          |
+| 3 Traffic from subscribers of the international telex service-to-mobile stations.....                                                          | 11          |
+| 3.1 Fully automatic operation .....                                                                                                            | 11          |
+| 3.2 Single-operator operation (direct access by a calling telex subscriber to a foreign land station) .....                                    | 11          |
+| 3.3 Semi-automatic operation (access by a calling subscriber to one's international centre for the establishment of a direct connection) ..... | 12          |
+| 3.4 Manual operation.....                                                                                                                      | 12          |
+| 3.5 Store-and-forward.....                                                                                                                     | 12          |
+
+|                                    | <i>Page</i>                                                                                                                                |    |
+|------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------|----|
+| 4                                  | Traffic exchanged between mobile stations .....                                                                                            | 13 |
+| 5                                  | Radiomaritime telex letter .....                                                                                                           | 13 |
+| 5.1                                | Definition .....                                                                                                                           | 13 |
+| 5.2                                | Operational procedures .....                                                                                                               | 13 |
+| 6                                  | Special provisions for the maritime mobile-satellite telex service .....                                                                   | 13 |
+| 6.1                                | Procedures for calls from subscribers of the international telex service to a mobile earth station ...                                     | 13 |
+| 6.2                                | Procedures for calls from MES to subscribers of the international telex service .....                                                      | 13 |
+| 6.3                                | Procedures for MES-to-MES calls .....                                                                                                      | 14 |
+| 6.4                                | Instructions for maritime mobile-satellite telex service .....                                                                             | 14 |
+| DIVISION D – RADIOTELEPHONE .....  |                                                                                                                                            | 15 |
+| 1                                  | General .....                                                                                                                              | 15 |
+| 1.1                                | Language to be used .....                                                                                                                  | 15 |
+| 1.2                                | Priority .....                                                                                                                             | 15 |
+| 1.3                                | Routing of calls .....                                                                                                                     | 15 |
+| 1.4                                | Information to be supplied, as necessary, by the calling party .....                                                                       | 15 |
+| 1.5                                | Call duration .....                                                                                                                        | 16 |
+| 1.6                                | Validity of requests .....                                                                                                                 | 16 |
+| 1.7                                | Exchange of radiotelegrams by radiotelephony .....                                                                                         | 16 |
+| 2                                  | Traffic from mobile stations to telephone subscribers .....                                                                                | 16 |
+| 2.1                                | Automatic operation .....                                                                                                                  | 16 |
+| 2.2                                | Single-operator operation .....                                                                                                            | 16 |
+| 2.3                                | Semi-automatic operation .....                                                                                                             | 17 |
+| 2.4                                | Manual operation .....                                                                                                                     | 17 |
+| 2.5                                | Operational procedures .....                                                                                                               | 17 |
+| 3                                  | Traffic from telephone subscribers to mobile stations .....                                                                                | 17 |
+| 3.1                                | Fully automatic operation .....                                                                                                            | 17 |
+| 3.2                                | Single-operator operation (direct access by a calling subscriber to a foreign land station) .....                                          | 17 |
+| 3.3                                | Semi-automatic procedure (access by a calling subscriber to one's international centre for the establishment of a direct connection) ..... | 18 |
+| 3.4                                | Manual operation .....                                                                                                                     | 18 |
+| 4                                  | Traffic exchanged between mobile stations .....                                                                                            | 19 |
+| 5                                  | Special provisions for the maritime mobile-satellite telephone service .....                                                               | 19 |
+| 5.1                                | Procedures for calls from subscribers of a terrestrial telephone network to a mobile earth station ..                                      | 19 |
+| 5.2                                | Procedures for calls from MES to subscribers of the terrestrial telephone networks .....                                                   | 19 |
+| 5.3                                | Procedures for MES-to-MES calls .....                                                                                                      | 20 |
+| 5.4                                | Instruction for maritime mobile-satellite telephone service .....                                                                          | 20 |
+| DIVISION E – RADIOTELEXOGRAM ..... |                                                                                                                                            | 21 |
+| 1                                  | General .....                                                                                                                              | 21 |
+| 1.1                                | Definition .....                                                                                                                           | 21 |
+| 1.2                                | Provision of service .....                                                                                                                 | 21 |
+| 1.3                                | Validity of requests .....                                                                                                                 | 21 |
+| 2                                  | Operational procedures .....                                                                                                               | 21 |
+| Bibliography .....                 |                                                                                                                                            | 22 |
+
+# **OPERATIONAL PROVISION FOR THE MARITIME MOBILE SERVICE**
+
+*(revised in 1996)*
+
+## **DIVISION A – GENERAL**
+
+### **1 Scope**
+
+**A1 1.1** This Recommendation provides for all aspects of operation of the radiotelegram service, the radiotelex service, the radiotelephone service and the radiotelexogram service in terms of both communications via maritime mobile satellite, and radio media of HF, MF, VHF and UHF<sup>1)</sup>.
+
+### **2 References**
+
+**A2 2.1** The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.
+
+- CCITT Recommendation E.105 (1992), *International telephone service*.
+- ITU-T Recommendation E.141 (1993), *Instructions for the international telephone service*.
+- CCITT Recommendation E.164 (1991), *Numbering plan for the ISDN era*.
+- CCITT Recommendation F.1 (1992), *Operational provisions for the international public telegram service*.
+- CCITT Recommendation F.17 (1992), *Operational aspects of service communications*.
+- CCITT Recommendation F.60 (1992), *Operational provisions for the international telex service*.
+- ITU-T Recommendation F.69 (1994), *The international telex service – Service and operational provisions of telex destination codes and telex network identification codes*.
+- ITU-T Recommendation F.72 (1993), *The international telex service – General principles and operational aspects of a store and forward facility*.
+- CCITT Recommendation F.111 (1991), *Principles of service for mobile systems*.
+- CCITT Recommendation F.120 (1988), *Ship station identification for VHF/UHF and maritime mobile-satellite services*.
+- ITU-T Recommendation D.90 (1995), *Charging, billing, international accounting and settlement in the maritime mobile service*.
+
+---
+
+<sup>1)</sup> This Recommendation constitutes part of a *Manual for Use by the Maritime Mobile and Maritime Mobile-Satellite Services* defined in *Radio Regulations*.
+
+### 3 Definitions
+
+- A3 3.1 For the purposes of this CCITT Recommendation, the following terms have the meanings defined below:
+- A4 3.1.1 **controlling operator:** The controlling operator is the first land-based operator handling the radiotelegram, radiotelex call or radiotelephone call in the direction from the mobile station.
+- A5 3.1.2 **accounting authority identification code:** An accounting authority identification code is assigned to each accounting authority (defined in the *International Telecommunication Regulations* [1]). In effect the accounting authority acts as a billing intermediary between mobile stations and ROAs.
+- A6 3.1.3 **recognized operating agency (ROA):** The term is defined in *the International Telecommunication Constitution* (Geneva, 1992) [2]. For the purpose of this CCITT Recommendation an ROA is, in effect, any individual, company, corporation or governmental agency that operates an international telecommunication service to carry public correspondence (as defined in the Constitution). Each ROA is authorized by an ITU Member, which imposes certain obligations on the ROA. (For further details, see the *Constitution*.)
+- A7 3.1.4 **land stations:** A station in the mobile service not intended to be used while in motion.
+- A8 3.1.5 **land earth station:** An earth station in the mobile-satellite service located at a specified fixed point or within a specified inland area to provide a feeder link for the mobile-satellite service.
+- A9 3.1.6 **mobile stations:** A station in the mobile service intended to be used while in motion or during halts at an unspecified point.
+- A10 3.1.7 **mobile earth station:** An earth station in the mobile-satellite service intended to be used while in motion or during halts at unspecified points.
+- A11 3.1.8 The term *land station/land earth station* and *mobile station/mobile earth station* should imply *coast station/coast earth station* and *ship station/ship earth station*, respectively used in the *Radio Regulations* [3].
+- A12 3.1.9 **ship station identity:** Ship's identification  $X_1, X_2 \dots X_n$  identifying the ship uniquely. The ship station identity may be transmitted on the radio path.
+- A13 3.1.10 **coast station identity:** The coast station identification  $X_1, X_2 \dots X_n$  transmitted on the radio path.
+- A14 3.1.11 **mobile station number:** The number that identifies a mobile station for access from a public network and forms part of the international number to be dialled or keyed by a public network subscriber.
+
+### 4 Order of priority
+
+- A15 4.1 The order of priority for communications in the maritime mobile service shall be as follows, except where impracticable in a fully automated system in which, nevertheless, communications described in A16 shall receive priority:
+- A16 a) distress calls, distress messages and distress traffic;
+- A17 b) communications preceded by the urgency signal;
+
+- A18 c) communications preceded by the safety signal;
+- A19 d) communications relating to radio direction-finding;
+- A20 e) communications relating to the navigation and safe movement of aircraft engaged in search and rescue operations;
+- A21 f) communications relating to the navigation, movements and need of ships, aircraft and weather observations messages destined for an official meteorological service;
+- A22 g) radiotelegrams relative to the application of the United Nations Charter (**ETATPRIORITE**);
+- A23 h) government radiotelegrams with priority (**ETATPRIORITE**) and government calls for which priority has been expressly requested;
+- A24 i) ordinary private radiotelegrams and **RCT** radiotelegrams for which urgent transmission and delivery has been requested;
+- A25 j) service communications relating to the operation<sup>2)</sup> of the telecommunication service or to communications previously exchanged;
+- A26 k) government communications other than those shown in A29 ordinary private communications and **RCT** radiotelegrams;
+- A27 l) radiomaritime letters.
+
+### 5 Limitations
+
+- A28 5.1 The duration of distress calls is not limited.
+- A29 5.2 Except in the automatic operation, the duration of private communications, and of government communications as the case may be, may be limited under certain circumstances (e.g. congestion or fault conditions). The ROAs concerned may agree to limit the duration of these communications.
+- A30 5.3 If the duration of services is limited, the caller shall be informed when calls are about to be connected, that it will be cut off after due time.
+
+### 6 Service hours
+
+- A31 6.1 While the services of most land stations are continuous, certain land stations may have a service of limited duration. It is recommended, therefore, to refer to the *List of Coast Stations* [4].
+- A32 6.2 The working hours of a mobile station in the maritime mobile service are dependent on the categories of ship stations as defined in the Radio Regulations. It is recommended to refer to the *List of Ship Stations* [5] as appropriate.
+
+---
+
+2) For the operational aspects of service telecommunications, see Recommendation F.17, which describes basic principles, acceptable content for service telecommunications and the principle of reciprocity regarding both service providers and services. More detailed provisions for specific telecommunication services may be found in Recommendations F.105, F.1 and F.60.
+
+## DIVISION B – RADIOTELEGRAMS
+
+### 1 Preparation and handing-in of radiotelegrams
+
+#### 1.1 Indication of station of origin
+
+- B1 1.1.1 When, because of duplication of names, the name of a station is followed by its call sign/ship station identity, the latter shall be joined to the name of the station by a fraction bar.
+
+Examples<sup>3)</sup>: **OREGON/OZOC** (not **OREGONOZOC**);
+
+**ROSE/DDOR** (not **ROSEDDOR**).
+
+- B2 1.1.2 When a land station retransmits a radiotelegram received from a mobile station, it shall transmit, as office of origin, the name of the mobile station in which the radiotelegram originated as this name appears in the *List of Ship Stations* [5], followed by its own name. Where appropriate, B1 shall also apply.
+- B3 1.1.3 In order to avoid any confusion with a telegraph office or a fixed station of the same name, the land station may, if desirable, complete the indication of the name of the mobile station of origin by the word **SHIP** or **AIRCRAFT**, placed before the station of origin.
+
+#### 1.2 Use of accounting authority identification codes by mobile stations
+
+- B4 1.2.1 The mobile station operator should, as a standard operating procedure, give the Accounting Authority Identification Code (AAIC) at the end of the preamble line. If the AAIC is missing, the land station operator should request **QRC**.
+
+#### 1.3 Time of handing-in
+
+- B5 1.3.1 In the transmission of radiotelegrams originating in a mobile station, the date and time of handing-in at this station are given by two groups of figures in the preamble line, the first indicating the day of the month (1 to 31) and the second consisting of a group of figures (0001 to 2400) indicating the hours and the minutes.
+- B6 1.3.2 The time of handing-in is indicated in Coordinated Universal Time (UTC).
+
+NOTE – For practical operating purposes, UTC may be considered as equivalent to Greenwich Mean Time (GMT).
+
+#### 1.4 Address
+
+- B7 1.4.1 The address of radiotelegrams destined for mobile stations should be as complete as possible and must include:
+- B8 a) the name or the designation of the addressee, with supplementary particulars, if necessary;
+- B9 b) the name of the mobile station followed, when necessary, by its call sign/ship station identity, the latter joined by a fraction bar to the name of the station as shown in the *List of Ship Stations* [5];
+- B10 c) the name of the land station through which the radiotelegram is to be forwarded, as it appears in the *List of Coast Stations* [4].
+- B11 1.4.2 If the mobile station does not appear in the *List of Ship Stations* [5], the sender should, if possible, indicate the nationality and route followed by the mobile station.
+
+---
+
+<sup>3)</sup> In the provision regarding the non-voice services, letters, figures and signs that are transmitted electrically are shown in bold font.
+
+**B12**    **1.4.3**    However, the name and call sign/ship station identity required under B10 may be replaced, at the risk of the sender, by particulars of the passage made by such a mobile station, indicated by the names of the ports or airports of departure and of destination, or by any equivalent indication.
+
+**B13**    **1.4.4**    Mobile stations may add to the name of the office of destination:
+
+- the name of the territorial subdivision; and/or
+- the destination country,
+
+if it is doubtful whether, without such addition, the radiotelegram could be correctly routed without difficulty.
+
+**B14**    **1.4.5**    The controlling operator retains or deletes the particulars in B13 or further amends the name of the office of destination as is necessary or sufficient for forwarding the radiotelegram to its proper destination.
+
+### **2 Counting of words**
+
+**B15**    **2.1**    The word count of the office of origin is decisive in the case of radiotelegrams destined for mobile stations, and that of the controlling operator is decisive in the case of radiotelegrams originating in mobile stations.
+
+**B16**    **2.2**    If two land stations participate in the handling of a radiotelegram, the decision of the controlling operator accepting the radiotelegram from the originating mobile station will prevail and will be valid for international accounting.
+
+### **3 Routing of radiotelegrams**
+
+**B17**    **3.1**    Radiotelegrams, originating in or destined to a mobile station should be routed via the land station that is considered most suitable in relation to the mobile station concerned in terms of the coverage and of the land station and radio conditions.
+
+**B18**    **3.2**    However, to expedite or to facilitate the routing of radiotelegrams to a land station, a mobile station may transmit them to another mobile station. The latter shall dispose of such radiotelegrams in the same manner as if they originated with itself (see B39 to B42).
+
+**B19**    **3.3**    If the sender of a radiotelegram handed in at a mobile station has indicated the land station to which the radiotelegram be sent, the mobile station shall, in order to effect this transmission to the land station indicated, wait, if necessary until the conditions specified in B17 and B18 are fulfilled.
+
+**B20**    **3.4**    In order to facilitate disposal of traffic, and subject to such conditions as individual ROAs may apply, land stations may, in exceptional circumstances and with discretion, without incurring additional charges, exchange radiotelegrams and service telegrams relating thereto.
+
+### **4 Transmission of radiotelegrams**
+
+#### **4.1 Routine repetition**
+
+**B21A**    **4.1.1**    Routine repetition means the repetition of isolated figures and mixed groups containing figures in the address and text parts. Any such repetition should be given after the text part and be preceded by the code **COL**.
+
+**B21B**    **4.1.2**    In view of CCITT Recommendation F.1 (A103) routine repetition may be used between land station and mobile station at the discretion of the sending station where the transmission conditions warrant it.
+
+**B21C**    **4.1.3**    Where a mobile station gives a routine repetition, the land station shall use the repeated groups to check the received address and text parts, but should not retransmit the routine repetition.
+
+#### 4.2 Doubtful reception
+
+B22 4.2.1 In the mobile service, when communication becomes difficult, the two stations in communication should make every effort to complete the radiotelegram in course of transmission. The receiving station may request not more than two repetitions of a radiotelegram of which the reception is doubtful.
+
+B23 4.2.2 If this triple transmission is ineffective, the radiotelegram is kept on hand in case a favourable opportunity for completing its transmission occurs.
+
+B24 4.2.3 If the transmitting station considers that it will not be possible to re-establish communications with the receiving station within twenty-four hours, it proceeds as follows:
+
+B25 4.2.4 If the transmitting station is a mobile station, it immediately informs the sender of the reason for the non-transmission of his radiotelegram. The sender may then request:
+
+B26 a) that the radiotelegram be transmitted through another land station or through other mobile stations; or
+
+B27 b) that the radiotelegram be held until it can be transmitted without additional charge; or
+
+B28 c) that the radiotelegram be cancelled.
+
+B29 4.2.5 If the transmitting station is a land station, it applies the provision of B43 to B52 to the radiotelegram.
+
+B30 4.2.6 When a mobile station subsequently transmits a radiotelegram thus held to the land station that incompletely received it, this new transmission must bear the service instruction **AMPLIATION** at the end of the preamble line of the radiotelegram.
+
+B31 4.2.7 However, if the radiotelegram is transmitted to another land station operated by the same ROA, the new transmission must bear, at the end of the preamble line, the service instruction **AMPLIATION VIA ...** (insert here the call sign/coast station identity of the land station to which the radiotelegram was transmitted in the first instance) and the ROA in question may claim only the charges relating to a single transmission.
+
+B32 4.2.8 The other land station, which thus forwards the radiotelegram, may claim from the mobile station of origin any additional charges resulting from the transmission of the radiotelegram between itself and the office of destination.
+
+B33 4.2.9 When the land station designated in the address as the station by which the radiotelegram is to be forwarded cannot reach the destination mobile station and has reason to believe that such mobile station is within the service area of another land station of the ROA by which it is operated, it may, if no additional charge is incurred thereby, forward the radiotelegram to this other land station.
+
+B34 4.2.10 A station of the mobile service that has received a radiotelegram and has been unable to acknowledge its receipt in the usual way must take the first favourable opportunity to give such acknowledgement.
+
+B35 4.2.11 When the acknowledgement of receipt of a radiotelegram transmitted between mobile station and land station cannot be given directly, it is forwarded through another mobile or land station by service advice (see Recommendation F.1, Division D) if the latter is able to communicate with the station that has transmitted the radiotelegram in question. In any case, no additional charge shall result.
+
+#### 4.3 Long distance radiocommunications
+
+B36 4.3.1 An ROA may organize a long-distance radiocommunication service between land station and mobile stations, with deferred acknowledgement of receipt or without any acknowledgement of receipt.
+
+B37 4.3.2 Each ROA designates the land station or stations participating in the long-distance radio service. An indication to this effect shall appear in the *List of Coast Stations* [4].
+
+B38 4.3.3 When there is doubt about the accuracy of any part of a radiotelegram transmitted under either of the systems mentioned in B36, the indication doubtful reception is entered on the copy delivered to the addressee, and the doubtful words or groups of words are underlined. If words are missing, blanks are left in the places where these words should be.
+
+#### 4.4 Routine retransmission by mobile stations
+
+B39 4.4.1 When a land station cannot reach the mobile station for which a radiotelegram is destined, the land station may, in order to forward the radiotelegram to its destination, have recourse to the help of another mobile station provided that the latter consents. The radiotelegram is then transmitted to this other mobile station. The help of the latter is given free of charge.
+
+B40 4.4.2 The same provision is also applicable to traffic from mobile stations to land stations, when necessary.
+
+B41 4.4.3 The station assisting in the free retransmission in accordance with B39 and B40 must enter the service abbreviation **QSP** ... (name or call sign/ship station identity of the mobile station) at the end of the preamble line of the radiotelegram.
+
+B42 4.4.4 In order that a radiotelegram thus forwarded may be considered as having reached its destination, the station that has made use of this indirect route must have obtained the regular acknowledgement of receipt, either direct or by an indirect route, from the mobile station for which the radiotelegram was destined or from the land station to which it was to be forwarded, as the case may be.
+
+#### 4.5 Period of retention of radiotelegrams at land stations
+
+B43 4.5.1 When it has not been possible for a land station to transmit a radiotelegram to a mobile station by the morning of the fifth day (not including the day of handing-in), the land station treats the radiotelegram as undelivered and notifies the office of origin accordingly.
+
+B44 4.5.2 The sender of a radiotelegram destined for a mobile station may specify the number of days during which the land station may hold the radiotelegram. In that case, the service indication **Jx** (x days), specifying the number of days (ten at the most) exclusive of the day of handing-in of the radiotelegram, shall be shown before the address. When it has not been possible for a land station to transmit a radiotelegram bearing the service indication **Jx** within the prescribed period, the land station treats the radiotelegram as undelivered and informs the office of origin accordingly.
+
+B45 4.5.3 The periods mentioned in B43 and B44 shall be ignored if the land station is sure that the mobile station will soon come within its service area.
+
+B46 4.5.4 On the other hand, the lapse of those periods is not awaited when the land station is sure that the mobile station, being in course of a voyage, either has definitely left its service area or will not enter it.
+
+B47 4.5.5 If there is reason to believe that no other land station of the ROA by which it is operated is or will be in touch with it, the land station cancels the radiotelegram as far as concerns the section between itself and the mobile station and informs the office of origin, which notifies the sender.
+
+B48 4.5.6 In the contrary case, the land station forwards the radiotelegram to the land station believed to be in touch with the mobile station, provided, however, that no additional charge results therefrom.
+
+B49 4.5.7 The land station that carries out the redirection alters the address of the radiotelegram by placing after the name of the mobile station that of the new land station charged with the transmission and adding at the end of the preamble line the service instruction **REDIRECTED FROM ... RADIO**, which must be transmitted throughout the course of the radiotelegram.
+
+B50 4.5.8 If, within the limits of the requisite period of retention of radiotelegrams, the land station that has redirected a radiotelegram to another land station is subsequently in a position to transmit the radiotelegram direct to the destination mobile station, it does so by inserting the service instruction **AMPLIATION** at the end of the preamble line.
+
+B51 4.5.9 It shall then transmit to the land station to which the radiotelegram had been redirected a service advice informing the latter of the transmission of the said radiotelegram.
+
+B52 4.5.10 When a radiotelegram cannot be transmitted to a mobile station owing to the arrival of the latter in a port near the land station, the latter station may, according to circumstances, forward the radiotelegram to the mobile station by other means of communication, at the same time informing the office of origin by service advice of the delivery.
+
+### 5 Advice of non-delivery
+
+- B53 5.1** When, for any reason, a radiotelegram originating in a mobile station and destined for a place on land cannot be delivered to the addressee, a service advice of non-delivery is addressed to the land station or the telegraph office that received the radiotelegram.
+- B54 5.2** After checking the address, the land station forwards the service advice, when possible, to the mobile station, if necessary by way of another land station of the same country or of a neighbouring country, as far as existing conditions or special agreements permit.
+- B55 5.3** When a radiotelegram received at a mobile station cannot be delivered, that station so informs the office or mobile station of origin by a service advice.
+- B56 5.4** In the case of a radiotelegram originating on land, this service advice is sent, whenever possible, to the land station through which the radiotelegram passed, or, if necessary, to another land station of the same country or of a neighbouring country, as far as existing conditions or special arrangements permit.
+- B57 5.5** In such cases the name or call sign/ship station identity of the station from which the radiotelegram was received is quoted.
+
+### 6 Radiomaritime letters
+
+- B58 6.1** An ROA may organize a service of radiomaritime letters between mobile stations and its land stations.
+- B59 6.2** Such correspondence is transmitted by radio between mobile and land stations.
+- B60 6.3** They may be forwarded on the land section:
+- B61 a)** wholly or partly by post (ordinary or airmail);
+- B62 b)** exceptionally by telefax or other electronic means, but with low priority.
+- B63 6.4** Routine retransmission by mobile stations of radiomaritime letters is not permitted.
+- B64 6.5** Radiomaritime letters shall be addressed only to places in the country in which the land station is situated, unless the *List of Coast Stations* [4] indicates that the station concerned will accept such traffic for onward transmission by post to places in other countries.
+- B65 6.6** Radiomaritime letters bear the service indication **SLT**. This indication precedes the address.
+- B66 6.7** Except as otherwise provided in B58 to B68, radiomaritime letters may be accepted, taking into account ITU-T CCITT Recommendations relating to letter telegrams if the telegram service is used to convey radiomaritime letters.
+- B67 6.8** The address must enable delivery to be effected without enquiry or requests for information. Registered or abbreviated code addresses may be accepted where B62 above applies, exceptionally, radiomaritime letters are forwarded by means of telegram on the land section.
+- B68 6.9** Radiomaritime letters rank, for radio transmission, after ordinary radiotelegrams on hand. Those that have not been transmitted within 24 hours of handing-in are sent concurrently with ordinary radiotelegrams.
+
+### 7 Special services
+
+- B69 7.1** Telegrams with special services of urgent transmission and de luxe form are admitted, provided that the ROAs concerned accept them.
+
+### 8 Special conditions relating to the maritime mobile-satellite service
+
+- B70 8.1** In the maritime mobile-satellite service radiotelegrams should normally be transmitted by radiotelex only.
+- B71 8.2** The radiotelegram service in B70 should be arranged in such a way that automatic retransmission is possible.
+
+## **DIVISION C – RADIOTELEX**
+
+### **1 General**
+
+#### **1.1 Routing of calls**
+
+**C1 1.1.1** A radiotelex call, originating in or destined to a mobile station should be set up via the land station that is considered to be most suitable in relation to the mobile station concerned in terms of the coverage and of the land stations and radio conditions.
+
+**C2 1.1.2** For radiotelex calls in the direction from land station to mobile station, originator should give, if possible, the approximate geographical position and should also indicate the land station to be used unless the ROA has established a specific route to be followed. Such requests should be respected as far as is practicable.
+
+**C3 1.1.3** For radiotelex calls in the direction from mobile station to land station, the mobile station may call a particular land station it desires to use. This land station should either handle the call itself or advise the mobile station to use another land station that is more suitable.
+
+#### **1.2 Information to be supplied, as necessary by the calling party**
+
+**C4 1.2.1** Calls from a subscriber of the international telex service to a mobile station:
+
+- a) international telex number and/or answer-back code of the calling telex subscriber;
+- b) telex number or mobile station number of the destination mobile station;
+- c) name or call sign/ship station identity of the destination mobile station;
+- d) international telex number and/or name of the land station to be used, or the approximate geographical position of the destination mobile station;
+- e) priority when specifically requested.
+
+**C5 1.2.2** Calls from a mobile station to a subscriber of the international telex service:
+
+- a) telex number or mobile station number of the calling mobile station;
+- b) the Accounting Authority Identification Code (AAIC) in accordance with CCITT Recommendation D.90 in the single-operator or manual operation;
+- c) destination country and/or network;
+- d) telex number and/or answer-back code of the destination telex subscriber;
+- e) priority when specifically requested.
+
+**C5A 1.2.3** C4 and C5 above apply to mobile station-to-mobile stations calls as appropriate.
+
+#### **1.3 Call duration**
+
+**C6 1.3.1** The chargeable duration of a call will be fixed at the end of the call:
+
+- a) by the controlling operator for a call originating from a mobile station;
+- b) for a call originating in the international telex service;
+  - by the land station operator in either manual or single-operator operation;
+  - by the operator of the international position of the originating country in the semi-automatic operation.
+
+**C7 1.3.2** For a call originating from a mobile station and where two land stations participate in the handling of the call, the decision of the controlling operator who has accepted the call from the originating mobile station shall prevail.
+
+C8      1.3.3      Should service difficulties be experienced in the course of a call, the chargeable duration shall be reduced automatically or manually to the total time during which transmission conditions were satisfactory, taking into account ITU-T Recommendations (F.60 and F.61).
+
+#### 1.4      **Validity of requests**
+
+C9      1.4.1      For a call to a mobile station where it becomes obvious that the required mobile station cannot be reached by the land station, the originating telex subscriber should be informed as soon as possible in order to have the opportunity to have the call cancelled if required. In any event, the caller should be informed no later than in the morning of the second day following the day on which the call request was made.
+
+C10     1.4.2      In the automatic service any information concerning unsuccessful call attempts shall be provided to the calling subscriber using the service signal format described in Recommendation F.60. The period of validity for store-and-forward messages in the automatic service shall be in accordance with Recommendation F.72.
+
+#### 1.5      **Exchange of radiotelegrams by radiotelex**
+
+C11     1.5.1      Stations of the maritime mobile service that are equipped for radiotelex may transmit and receive radiotelegrams by means of radiotelex.
+
+C12     1.5.2      Stations of the maritime mobile-satellite service should normally transmit and receive radiotelegrams by means of radiotelex only.
+
+### 2      **Traffic from mobile stations to subscribers of the international telex service**
+
+#### 2.1      **Automatic operation**
+
+C13     2.1.1      Whenever possible, fully automatic procedures should be used.
+
+C14     2.1.2      For a call originating from a mobile station and after connection with the desired land station is established, the mobile station should forward the international telex number, including the telex destination code in accordance with Recommendation F.69. The selection procedures for calls from a mobile station in the maritime mobile-satellite service to a subscriber of the international telex service are described in clause 6 of Division C.
+
+#### 2.2      **Single-operator operation**
+
+C15     2.2.1      The land station operator should select the destination telex subscriber directly via the international telex network if fully automatic procedures (C13) are not possible.
+
+#### 2.3      **Semi-automatic operation**
+
+C16     2.3.1      The destination telex subscriber should be automatically selected if fully automatic procedures (C13) or single operator procedures (C15) cannot be applied.
+
+#### 2.4      **Manual operation**
+
+C17     2.4.1      The land station operator should apply manual procedures if fully automatic (C13), single-operator (C15) or semi-automatic (C16) procedures are not possible.
+
+#### 2.5      **Store-and-forward service**
+
+C17A    2.5.1      The mobile station should transmit the message to the land station using automatic procedures. The land station should forward the message via the international telex network to the destination telex subscriber.
+
+C17B    2.5.2      The procedures for store-and-forward in the operation international telex network, as laid down in Recommendations F.72, U.80 and U.81, should be taken into account.
+
+#### **2.6 Operational procedures**
+
+**C18 2.6.1** The manual, semi-automatic and fully automatic procedures for the international telex service, as laid down in Recommendations F.60 and F.61, should be taken into account.
+
+### **3 Traffic from subscribers of the international telex service-to-mobile stations**
+
+#### **3.1 Fully automatic operation**
+
+**C19 3.1.1** Whenever possible fully automatic procedures should be used.
+
+**C20 3.1.2** A subscriber of the international telex service should forward the international telex number of the destination mobile station including the mobile station number and if necessary the telex destination code of the ocean region in which the mobile station is thought to be located. The call will then be routed, through an appropriate land station to the destination mobile station. The selection procedures for calls from a subscriber of the international telex service to mobile earth station are described in clause 6 of Division C.
+
+**C21 3.1.3** If the originating telex subscriber, for some technical reason, cannot use fully automatic procedures to establish contact with the mobile station, semi-automatic (C35) or single-operator (C24) procedures should be used.
+
+**C22 3.1.4** On international telex links a destination code in accordance with Recommendation F.69 will be used unless otherwise agreed bilaterally.
+
+**C23 3.1.5** Normal telex procedure should be forwarded once the connection between the subscriber of the international telex service and the mobile service and the mobile station has been established.
+
+#### **3.2 Single-operator operation (direct access by a calling telex subscriber to a foreign land station)**
+
+##### **3.2.1 Booking**
+
+**C24 3.2.1.1** If automatic operation (C19) is not possible and where an ROA allows its subscribers to book a call directly with a land station in another country, the originating telex subscriber should select the desired foreign land station, when known, using automatic procedures and submit the call details to the land station operator.
+
+**C25 3.2.1.2** The charges fixed by the land station operator should be levied on the calling subscriber through international accounting.
+
+**C26 3.2.1.3** In addition to the information in C4, the calling subscriber should designate the originating national telex network.
+
+**C27 3.2.1.4** As an alternative to C25 and C26, a land station may accept direct calls from foreign subscribers in other countries provided that the calling telex subscriber supplies the name and address of a party in the country in which the land station is located who will take responsibility for the payment of charges.
+
+**C28 3.2.1.5** The procedures described in C25 and C27 may only be applied when an appropriate bilateral agreement exists between the two ROAs concerned. If such an agreement does not exist, the land station should refuse such calls to avoid accounting difficulties.
+
+**C29 3.2.1.6** In C24 and C27 above, the call to the foreign land station will be charged as an ordinary international telex call for its entire duration, regardless of whether it merely serves the purpose of booking the radiotelex call or whether the land station can extend the connection to the mobile station without having to recall the originating subscriber.
+
+##### **3.2.2 Setting-up**
+
+**C30 3.2.2.1** When the connection to the destination mobile station can be immediately established, the originating telex subscriber should be released by the land station. When appropriate, the land station operator should recall the originating telex subscriber using automatic procedures. In this particular case, the country in which the land station is located is to be considered as the outgoing country for the call.
+
+**C31 3.2.2.2** In case C30, the land station should include in the maritime bill:
+
+- a) the landline charge;
+- b) the land station charge.
+
+**C32 3.2.2.3** When the connection to the destination mobile station can be immediately established, the maritime bill made out by the land station operator should include only the land station charge.
+
+**C33 3.2.2.4** All information regarding collection of charges for single-operator calls (see C15) should be submitted by the land station ROA on a regular basis to be determined by the ROAs involved.
+
+**C34 3.2.2.5** The methods to be used in collecting the charges are described in Recommendation D.90.
+
+#### **3.3 Semi-automatic operation (access by a calling subscriber to one's international centre for the establishment of a direct connection)**
+
+**C35 3.3.1** If fully automatic (C19) or single-operator (C24) procedures are not possible, the telex operator of the outgoing international centre should receive the booking and selects the mobile station directly. The procedures of Recommendation F.60 should be applied.
+
+#### **3.4 Manual operation**
+
+##### **3.4.1 Booking**
+
+**C36 3.4.1.1** If fully automatic (C19), single-operator (C24) or semi-automatic (C35) procedures are not available, the originating telex subscriber should make his booking at the international telex centre of the outgoing country or network.
+
+**C37 3.4.1.2** Where conditions permit, the international telex position should select directly the appropriate foreign land station. Alternatively, the international telex position of the outgoing country or network should contact the international telex position in the country or network in which the desired land station is located for the necessary assistance to obtain contact with the land station.
+
+##### **3.4.2 Setting-up**
+
+**C38 3.4.2.1** The land station operator will establish a connection with the originating telex subscriber either directly or with the assistance of the own international telex position in the country of the land station.
+
+**C39 3.4.2.2** Within 24 hours of the call's termination, the land station shall pass the following information to the international telex position of the origin country, where it is recorded for charging and accounting purposes:
+
+- a) the calling subscriber's telex number;
+- b) the mobile station's call sign/ship station identity;
+- c) the chargeable duration of the call;
+- d) the land station charge to be collected.
+
+#### **3.5 Store-and-forward**
+
+**C39A 3.5.1** The originating telex subscriber should select the appropriate land station and deposit the message using the procedures desired in Recommendations F.72 and U.80.
+
+### 4 Traffic exchanged between mobile stations
+
+C39B 4.1 Provisions from C13 to C39A apply to traffic exchanged between mobile stations.
+
+### 5 Radiomarine telex letter
+
+#### 5.1 Definition
+
+C40 5.1.1 **Radiomarine telex letter:** A message sent by radiotelex direct from a mobile station to a selected land station or to a selected public telegraph office for delivery by mail or any other appropriate means.
+
+#### 5.2 Operational procedures
+
+C41 5.2.1 The mobile station should select the access code allocated for the radiomarine telex letter service, or the access code allocated for the fully automatic telex service followed, if appropriate, by the telex number of the selected land station telegraph office.
+
+C42 5.2.2 The mobile station should supply the following information:
+
+- international telex number of the mobile station or mobile station number (as provided in Recommendation F.125);
+- the Accounting Authority Identification Code (AAIC);
+- destination name and address;
+- the words "RADIOMARITIME TELEX LETTER".
+
+### 6 Special provisions for the maritime mobile-satellite telex service
+
+#### 6.1 Procedures for calls from subscribers of the international telex service to a mobile earth station
+
+C43 6.1.1 To establish a call from subscribers of the international telex service to Mobile Earth Stations (MES), the calling telex subscriber should select the telex destination code of the appropriate satellite region followed by the mobile station number.
+
+C44 6.1.2 The originating telex subscriber, when calling an MES, should input the following selection information, plus any necessary prefix and end-of-selection signal:
+
+**58STX<sub>1</sub> ..... X<sub>n</sub>**
+
+where:
+
+**58S** is the telex destination code in accordance with Recommendation F.69 (S = 1, 2, 3 or 4);
+
+**T** is the T-digit in accordance with Recommendation F.125; and
+
+**X<sub>1</sub> ..... X<sub>n</sub>** are part of the MES identity in accordance with Recommendation F.125.
+
+To meet the requirements of the international telex service and in particular the signalling conditions specified in Recommendations U.11 and U.12, the Inmarsat mobile station number should not contain more than 9 digits.
+
+#### 6.2 Procedures for calls from MES to subscribers of the international telex service
+
+##### 6.2.1 Setting up a communication channel
+
+C45 6.2.1.1 The necessary communication channel should be set up in accordance with the procedures established by the appropriate satellite organization.
+
+##### 6.2.2 Information to be provided
+
+**C46** **6.2.2.1** The MES should provide all information necessary for setting up the call to the destination telex subscriber. Such information may include:
+
+- international telex number of the destination telex subscriber;
+- desired land earth station whether or not the land earth station is located in the country of the called telex subscriber;
+- supplementary service requests.
+
+The information in a) is required for all calls. The information in b) and c) may be required on some calls, e.g. if the user requests a specific routing of the call or if specific service characteristics are to be applied.
+
+##### 6.2.3 Calling a subscriber of the international telex service
+
+**C47** **6.2.3.1** The MES should select the access code 00 followed by the full international telex number of the destination telex subscriber. Hence the numbering sequence selected by MES should be of the form:
+
+**00 <F.69> <national telex number>+**
+
+where:
+
+|                                      |                                                                             |
+|--------------------------------------|-----------------------------------------------------------------------------|
+| <b>00</b>                            | Access code for automatic call                                              |
+| <b>&lt;F.69&gt;</b>                  | 2- or 3-digit telex destination code in accordance with Recommendation F.69 |
+| <b>&lt;national telex number&gt;</b> | National number of the destination telex subscriber                         |
+| <b>+</b>                             | End of selection                                                            |
+
+**C48** **6.2.3.2** It may be possible to select specific supplementary services associated with the call by use of access codes other than 00, for example:
+
+|                                                                  |                                                                             |
+|------------------------------------------------------------------|-----------------------------------------------------------------------------|
+| <b>A<sub>1</sub>A<sub>2</sub></b>                                | Access code including supplementary service requests                        |
+| <b>&lt;F.69&gt;</b>                                              | 2- or 3-digit telex destination code in accordance with Recommendation F.69 |
+| <b>&lt;national telex number&gt; N<sub>1</sub>-N<sub>n</sub></b> | National number of the destination telex subscriber                         |
+| <b>+</b>                                                         | End of selection                                                            |
+
+**C49** **6.2.3.3** The operational procedures should permit the MES to choose land earth stations through which the call is to be routed, for example, in order to minimize call charges.
+
+**C50** **6.2.3.4** The provision of C3 notwithstanding, the land earth station called should always handle the call whenever a MES is within the coverage area of the land earth station.
+
+#### 6.3 Procedures for MES-to-MES calls
+
+**C51** **6.3.1** A MES participating in the mobile satellite telex service may send a message to another MES. Selection procedures for MES-to-MES calls which are carried by the international telex service should be similar to those for calls from a MES to subscribers of the international telex service as described in C47. This format will be used whether or not the MESs are in the same satellite region.
+
+**C52** **6.3.2** The procedures for calls between MESs in the same satellite region, or in satellite regions served by the same LES and which do not utilize the international telex service are not the subject for international standardization.
+
+#### 6.4 Instructions for maritime mobile-satellite telex service
+
+**C53** **6.4.1** The general principles laid down in Recommendation F.60 apply also to the maritime mobile-satellite telex service. The instructions should contain the full procedures.
+
+## **DIVISION D – RADIOTELEPHONE**
+
+### **1 General**
+
+#### **1.1 Language to be used**
+
+**D1 1.1.1** Where applicable and where language difficulties exist, the abbreviations and signals in related provisions of *Radio Regulations* [3] should be used in radiotelephone communications between land stations and mobile stations.
+
+#### **1.2 Priority**
+
+**D2 1.2.1** Apart from the general order of priority shown in **A15 to A27**, radiotelephone calls shall have precedence in the terrestrial network, so far as possible, over other telephone calls of the same class.
+
+#### **1.3 Routing of calls**
+
+**D3 1.3.1** A radiotelephone call, originating in or destined to a mobile station, should be set up via the land station that is considered to be the most suitable in relation to the mobile station concerned in terms of the coverage and of the land station and radio condition.
+
+**D4 1.3.2** For radiotelephone calls in the direction from land station to mobile station, the caller should give the one approximate geographical position if possible and may also indicate the land station to be used unless the ROA has established a specific route to be followed. Such requests should be respected as far as is practicable.
+
+**D5 1.3.3** For radiotelephone calls in the direction from mobile station to land station, the mobile station may call a land station it desires to use. This land station shall either handle the call itself or advise the mobile station to use another land station that is more suitable.
+
+#### **1.4 Information to be supplied, as necessary, by the calling party**
+
+**D6 1.4.1** Calls from a telephone subscriber to a mobile station:
+
+- a) complete telephone number of the calling subscriber;
+- b) appropriate identification of the mobile station;
+- c) name of the land station to be used or the approximate geographical position of the destination mobile station;
+- d) name of the called party, if applicable. All calls to mobile stations in the maritime mobile service are treated as personal calls, with the possible exception of the maritime mobile-satellite service;
+- e) priority when specifically requested.
+
+**D7 1.4.2** Call from a mobile station to a telephone subscriber:
+
+- a) appropriate identification of the mobile station;
+- b) the Accounting Authority Identification Code (AAIC) in accordance with Recommendation D.90 in the single-operator or manual operation;
+- c) the information specified in Article 63 of the *Instructions for the International Telephone Service*;
+- d) priority when specifically requested.
+
+**D7A 1.4.3** D6 and D7 above apply to mobile station-to-mobile station calls as appropriate.
+
+#### **1.5 Call duration**
+
+**D8 1.5.1** The chargeable duration of a call shall be fixed at the end of the call:
+
+- a) by the controlling operator for a call originating from a mobile station;
+- b) for a call originating in the terrestrial telephone network;
+  - by the land station operator in manual or single-operator operation;
+  - by the operator of the international position of the outgoing country in the semi-automatic operation.
+
+**D9 1.5.2** For a call originating from a mobile station where two land stations participate in the handling of the call, decision of the controlling operator that has accepted the call from the originating mobile station shall prevail.
+
+**D10 1.5.3** Should service difficulties be experienced in the course of a call, the chargeable duration shall be reduced automatically or manually to the total time during which transmission conditions were satisfactory, taking into account ITU-T Recommendations.
+
+#### **1.6 Validity of requests**
+
+**D11 1.6.1** If not cancelled by the caller or refused by the called party, requests for calls from land to mobile stations:
+
+- a) in the VHF and MF bands shall remain valid until 0800 local time on the day following the day on which the request was made;
+- b) in the HF band shall remain valid until 0800 local time on the second day following the day on which the request was made.
+
+**D12 1.6.2** However, if it becomes obvious that the required mobile station is outside the coverage area of the land station, the caller shall be informed as soon as possible in order to have the call cancelled.
+
+**D13 1.6.3** All requests for calls from mobile to land stations shall be cancelled where the call is not immediately attended to or on completion of the successive attempts provided for by the rules of each ROA, unless there has been an express request to the contrary by the calling mobile station, which shall be able to determine the waiting period for listening in on the land station frequency with a view to making a further attempt to set up the call.
+
+#### **1.7 Exchange of radiotelegrams by radiotelephony**
+
+**D14 1.7.1** Stations of the maritime mobile service that are equipped for radiotelephony may transmit and receive radiotelegrams by means of radiotelephony. Stations of the maritime mobile-satellite service should normally transmit and receive radiotelegrams by means of radiotelex only.
+
+### **2 Traffic from mobile stations to telephone subscribers**
+
+#### **2.1 Automatic operation**
+
+**D15 2.1.1** Whenever possible, fully automatic procedures should be used.
+
+**D16 2.1.2** For a call originating from a mobile station and after connection with the desired land station has been established, the mobile station should forward the appropriate telephone country code (Recommendation E.164) and the number of the subscriber of an ROA's telephone network. The selection procedures for calls in the maritime mobile-satellite service, see clause 4 of Division D.
+
+#### **2.2 Single-operator operation**
+
+**D17 2.2.1** The land station operator should select the called subscriber directly via the automatic telephone networks if automatic procedures (D15) are not possible.
+
+#### **2.3 Semi-automatic operation**
+
+**D18 2.3.1** The called telephone subscriber should be automatically selected by a telephone operator in the country in which land station is situated if fully automatic (D15) or single-operator (D17) procedures cannot be applied.
+
+#### **2.4 Manual operation**
+
+**D19 2.4.1** The land station operator should apply manual procedures if fully automatic (D15), single-operator (D17) or semi-automatic (D18) procedures are not possible.
+
+#### **2.5 Operational procedures**
+
+**D20 2.5.1** The fully automatic, semi-automatic and manual procedures for the terrestrial telephone network, as laid down in Recommendations E.105 and E.140 and the *Instructions for the International Telephone Service* [6] should be taken into account.
+
+### **3 Traffic from telephone subscribers to mobile stations**
+
+#### **3.1 Fully automatic operation**
+
+**D21 3.1.1** Whenever possible, fully automatic procedures should be used.
+
+**D22 3.1.2** The subscriber of an ROA's telephone network should select the appropriate international telephone number, which would include the mobile station number. The call routing will be determined by the appropriate country code which is chosen and which will form part of the international telephone number (see D41). The call will then be routed through an appropriate land station to the destination mobile station. The selection procedures for calls from a subscriber of the international telephone service are described in clause 5 of Division D.
+
+**D23 3.1.3** If the calling subscriber, for some technical reason, cannot use fully automatic procedures to establish contact with mobile station, semi-automatic or single operator procedures should be used.
+
+#### **3.2 Single-operator operation (direct access by a calling subscriber to a foreign land station)**
+
+##### **3.2.1 Booking**
+
+**D24 3.2.1.1** If fully automatic operation is not possible and where an appropriate bilateral agreement between ROA's allows its subscriber to book a call directly with a land station in another country, the calling telephone subscriber should select desired foreign land station, where known, using automatic procedures and submit the call details to the land station operator. If such an agreement does not exist, the land station should refuse such calls to avoid accounting difficulties.
+
+**D25 3.2.1.2** The charges fixed by the land station operator should be levied on the calling subscriber through international accounting.
+
+**D26 3.2.1.3** In addition to the information in D6, the calling subscriber must designate his country and national telephone number.
+
+**D27 3.2.1.4** As an alternative to D25, land stations may accept direct calls from telephone subscribers in other countries provided that the calling telephone subscriber supplies the name and address of a party in the country, in which the land station is located, who will take responsibility for the payment of charges.
+
+**D28 3.2.1.5** The procedures described in D25 and D27 may only be applied when an appropriate bilateral agreement exists between the two ROAs concerned.
+
+**D29 3.2.1.6** D24 and D27 above, the call to the foreign land station will be charged as an ordinary international telephone call for its entire duration, regardless of whether it merely serves the purpose of booking the radiotelephone call or whether the land station can extend the connection to the mobile station without having to recall the originating subscriber.
+
+##### **3.2.2 Setting-up**
+
+**D30 3.2.2.1** When demand operation cannot be used, the calling telephone subscriber will be disconnected by the land station. When the land station operator then recalls the caller using automatic direct selection, the land station country is considered as the outgoing country for the call.
+
+**D31 3.2.2.2** In case D30, the land station includes in the maritime bill:
+
+- a) the land-line charge;
+- b) the land station charge.
+
+**D32 3.2.2.3** When demand operation has been used, the maritime bill made out by land station operator includes only:
+
+- the land station charge.
+
+**D33 3.2.2.4** All information regarding collection of charges for single-operator calls (see D17) should be submitted by the land station ROA on a regular basis to be determined by the ROAs involved.
+
+**D34 3.2.2.5** The methods to be used in collecting the charges are described in Recommendation D.90.
+
+#### **3.3 Semi-automatic procedure (access by a calling subscriber to one's international centre for the establishment of a direct connection)**
+
+**D35 3.3.1** If automatic (D21) or single-operator (D24) procedures are not possible, the telephone operator of the international centre of the outgoing country receives the booking and selects the mobile station directly. Normal international semi-automatic telephone procedures shall be applied.
+
+#### **3.4 Manual operation**
+
+##### **3.4.1 Booking**
+
+**D36 3.4.1.1** If automatic (D21), single-operator (D24) or semi-automatic (D35) procedures cannot be applied, the subscriber should make his booking at an international centre in the outgoing country.
+
+**D37 3.4.1.2** If conditions permit, an international position should select the foreign land station in question directly. Otherwise an international position in the land station country should be selected to give the necessary assistance to obtain contact with the land station in question. Alternatively, the international telephone position of the outgoing country or network should contact the international telephone position in the country of network in which the desired land station is located for the necessary assistance to obtain contact with the land station.
+
+##### **3.4.2 Setting-up**
+
+**D38 3.4.2.1** The land station operator will establish a connection with the originating telephone subscriber either directly or with the assistance of his own international telephone position.
+
+**D39 3.4.2.2** After the termination of the call, the land station shall pass the following information to the international telephone position of the country of origin, where it is recorded for charging and accounting purposes:
+
+- a) the calling subscriber's telephone number;
+- b) the mobile station's name and/or appropriate identification;
+- c) the chargeable duration of the call;
+- d) the land station charge to be collected.
+
+**D40 3.4.2.3** Alternatively all information regarding collection of charges should be submitted to the caller's ROA on a regular basis to be determined by the ROAs involved.
+
+### **4 Traffic exchanged between mobile stations**
+
+**D40A 4.1** Provisions from D15 to D40 apply to traffic exchanged between mobile stations as appropriate.
+
+### **5 Special provisions for the maritime mobile-satellite telephone service**
+
+#### **5.1 Procedures for calls from subscribers of a terrestrial telephone network to a mobile earth station**
+
+**D41** To establish a call from a telephone subscriber to a Mobile Earth Station (MES), the calling telephone subscriber should select the international mobile number appropriate to the mobile system being accessed. The international mobile number may vary according to the maritime mobile-satellite system offering the service. Where the system provides service on the basis of individual satellite regions, the originating subscriber should select the international mobile number which will contain the telephone country code for the appropriate satellite region followed by the MES number. Where the system offers service on the basis Single Network Access Code operation (SNAC), the originating subscriber should select the international mobile number which will contain the appropriate telephone country code for worldwide access followed by the MES number.
+
+**D42** The selection information for the Inmarsat systems providing service on the basis of either satellite regions or SNAC operation may be located in CCITT Recommendation E.215.
+
+#### **5.2 Procedures for calls from MES to subscribers of the terrestrial telephone networks**
+
+##### **5.2.1 Setting up a communication channel**
+
+**D43** The necessary communication channel should be set up in accordance with the procedures established by the appropriate satellite organization.
+
+##### **5.2.2 Information to be provided**
+
+**D44** The MES should provide all information necessary for setting up the call to the called subscriber:
+
+- a) called party address international telephone number of the called subscriber including any prefix;
+- b) desired land earth station whether or not the land earth station is located in the country of the called subscriber;
+- c) selection of a specific ROA (for further study);
+- d) bearer service/teleservice characteristics, including supplementary service requests.
+
+The information in a) is required for all calls. The information in b) and c) may be required on some calls, e.g. if the user requests a specific routing of the call or if specific service characteristics are to be applied.
+
+##### **5.2.3 Calling a telephone subscriber**
+
+**D45 5.2.3.1** The MES should select the prefix 00 followed by the full international telephone or ISDN number of the called telephone subscriber. Hence, the numbering sequence selected by a MES should be of the form:
+
+$$00I_1I_2I_3N_1 \dots N_n$$
+
+where:
+
+**00** Prefix for automatic call
+
+**$I_1I_2I_3$**  1-, 2- or 3-digit country code in accordance with Recommendation E.164
+
+**$N_1 \dots N_n$**  National (subscriber) telephone number
+
+**D46**    **5.2.3.2**   It may also be possible to select specific services associated with the call by use of prefixed numbers other than 00. For example:
+
+**P<sub>1</sub>P<sub>2</sub>**            Prefix
+
+**I<sub>1</sub>I<sub>2</sub>I<sub>3</sub>**            1-, 2- or 3-digit country code in accordance with Recommendation E.164
+
+**N<sub>1</sub> ... N<sub>n</sub>**        National (subscriber) telephone number
+
+**D47**    **5.2.3.3**   The operational procedures should allow the MES to choose the land earth station through which the call is to be routed, for example, in order to minimize call charges.
+
+**D48**    **5.2.3.4**   The provision of D5 notwithstanding, the land earth station called should always handle itself the ship-to-shore call whenever the calling ship earth station is within the coverage area of the land earth station.
+
+##### **5.2.4    Access to special destination, services or facilities**
+
+**D49**    **5.2.4.1**   The MES will have access to a special destination, service or facility by selecting a special prefix otherwise allocated.
+
+**D50**    **5.2.4.2**   Each ROA may decide which special destinations, services or facilities to provide, where they are to be located and how the call would be routed.
+
+**D51**    **5.2.4.3**   An example of general selection sequence will be as follows:
+
+$$D_1D_2I_1I_2I_3X_1X_2$$
+
+where:
+
+**D<sub>1</sub>D<sub>2</sub>**            Prefix, identifying the category and type of special destinations, service or facilities
+
+**I<sub>1</sub>I<sub>2</sub>I<sub>3</sub>**            Optional country code
+
+**X<sub>1</sub>X<sub>2</sub>**            Other optional digits
+
+#### **5.3    Procedures for MES-to-MES calls**
+
+**D52**    **5.3.1**    A MES participating in the mobile satellite telephone service may send a call to another MES. Selection procedures for MES-to-MES calls which are carried by the ROA's telephone service should be similar to those for calls from a MES to telephone subscriber, as described in D44. This format will be used whether or not MESs are in the same satellite region.
+
+**D53**    **5.3.2**    Each ROA operating a land earth station may decide whether to switch ship-to-ship traffic within satellite region at the land earth station or at an international telephone exchange. The procedures for calls between MESs in the same satellite region, or in satellite regions served by the same land earth station and which do not utilize the ROA's telephone service are not the subject of international standardization.
+
+#### **5.4    Instruction for maritime mobile-satellite telephone service**
+
+**D54**    **5.4.1**    For telephone subscribers the general principles laid down in Recommendation E.120 apply also to the maritime mobile-satellite telephone service. The instructions should contain the full selection procedures.
+
+## **DIVISION E – RADIOTELEXOGRAM**
+
+### **1 General**
+
+#### **1.1 Definition**
+
+- E1**    **1.1.1**    A **radiotelexogram** is a message sent by telex or telefax direct from an originator subscriber to a foreign land station for transmission to a mobile station or a message sent from a mobile station to a land station for transmission directly to a telefax or telex subscriber (see Note in E5).
+
+#### **1.2 Provision of service**
+
+- E2**    **1.2.1**    Operating, charging and accounting procedures should be subject to a bilateral agreement between the ROAs concerned. If such an agreement does not exist, the land station should refuse such radiotelexograms in the shore-to-ship direction.
+- E3**    **1.2.2**    Alternatively, land stations may accept radiotelexograms from foreign originators provided that the calling subscriber supplies the name and address of a party in the land station country that will take responsibility for the payment of charges.
+
+#### **1.3 Validity of requests**
+
+- E4**    **1.3.1**    If it becomes obvious that the required mobile station is outside the coverage area of the land station, the originator shall be informed as soon as possible in order to have the radiotelexogram cancelled.
+
+### **2 Operational procedures**
+
+- E5**    **2.1**    The transmission of radiotelexograms should be in accordance with Divisions **B** and **C** or other ITU-T Recommendations as appropriate except as specified below or where varied through bilateral agreement.
+
+NOTE – A radiotelexogram is different from a radiotelex or telefax call. In particular, a radiotelexogram is normally transmitted between the mobile station and the land station as a radiotelegram by Morse telegraphy or by radiotelephony.
+
+- E6**    **2.2**    Information to be supplied to the land station, as necessary, by the originator.
+
+#### **E7**    **2.2.1**    Radiotelexogram to a mobile station:
+
+- a) international telex number and/or answer-back code or the telefax number of the calling subscriber;
+- b) the date and time of origin;
+- c) the word RADIOTELEXOGRAM;
+- d) name or designation of the addressee with supplementary particulars if necessary;
+- e) the name of the mobile station followed, when necessary, by its call sign/ship station identity or where this is not known, the particulars of the passage made by the mobile station;
+- f) any specific delivery instructions.
+
+#### **E8**    **2.2.2**    Radiotelexogram from a mobile station:
+
+- a) name and/or call sign/ship station identity of the mobile station;
+- b) identification of the accounting authority;
+- c) the date and time of origin;
+- d) the word RADIOTELEXOGRAM;
+- e) destination country and/or network;
+- f) called subscriber's telex number and answer-back code or telefax number.
+
+## **Bibliography**
+
+- [1] *International Telecommunication Regulations*, ITU, Geneva, 1992.
+- [2] *International Telecommunication Constitutions*, ITU, Geneva, 1992.
+- [3] *Radio Regulations*, ITU, Geneva, 1994.
+- [4] *List of Coast Stations*, ITU, Geneva, 1993.
+- [5] *List of Ship Stations*, ITU, Geneva, 1995.
+- [6] *Instructions for the International telephone service*, ITU, Geneva, 1993.

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' in a bold, sans-serif font.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.122**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**OPERATIONS AND QUALITY OF SERVICE  
+MOBILE SERVICE**
+
+---
+
+**OPERATIONAL PROCEDURES FOR  
+THE MARITIME SATELLITE DATA  
+TRANSMISSION SERVICE**
+
+**ITU-T Recommendation F.122**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation F.122 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **OPERATIONAL PROCEDURES FOR THE MARITIME SATELLITE DATA TRANSMISSION SERVICE**
+
+## **1 Introduction**
+
+1.1 The purpose of this Recommendation is:
+
+- a) to standardize the procedures for subscribers of a public data network (PDN) calling ship earth stations in the Maritime Satellite Data Transmission Service;
+- b) to standardize the procedures for calling subscribers of a PDN from ship earth stations using the packet switched data transmission service defined in Recommendations X.25 and X.352;
+- c) to standardize the procedures for calling subscribers of a PDN from ship earth stations by accessing packet assembly/disassembly facilities (PAD) as defined in Recommendation X.351.
+
+*Note 1* - This Recommendation does not cover data calls passed through the international public switched telephone network other than those which are accessed through PADs designed in accordance with Recommendation X.351.
+
+*Note 2* - Procedures for subscribers of a PDN calling a ship earth station by accessing a PAD are for further study.
+
+1.2 Related CCITT Recommendations are:
+
+- E.200/F.110 Operational provisions for the maritime mobile service.
+- E.210/F.120 Ship station identification for VHF/UHF and Maritime Mobile-Satellite Services.
+- E.215 Telephone/ISDN numbering plan for the Mobile-Satellite Service of INMARSAT.
+- E.216 Selection procedure for the INMARSAT mobile-satellite telephone and ISDN services.
+- F.125 Telex numbering plan for the Mobile-Satellite Service of INMARSAT.
+- F.126 Selection procedures for the INMARSAT Mobile-Satellite Telex Service.
+- X.1 International user classes of service in public data networks and ISDNs.
+- X.2 International data transmission services and optional user facilities in public data networks.
+- X.96 Call progress signals in public data networks.
+- X.121 International numbering plan for public data networks.
+- X.180 Administrative arrangements for international closed user groups (CUGs).
+- X.300 General principles and arrangements for interworking between public data networks, and between public data networks and other public networks.
+- X.350 General interworking requirements to be met for data transmission in the international public mobile satellite systems.
+- X.351 Special requirements to be met for packet assembly/disassembly facilities (PADS) located at or in association with coast earth stations in the Maritime Satellite Service.
+- X.352 Interworking between packet switched public data networks and the public maritime mobile satellite data transmission system.
+- X.353 Routing principles for interworking public maritime mobile satellite data transmission systems in the public data network.
+
+1.3 The following basic considerations were taken into account when formulating this Recommendation:
+
+- a) Each ship is allocated a unique 9-digit INMARSAT mobile number.
+
+*Note* - The first generation maritime mobile satellite (INMARSAT) system also caters for a 7-digit INMARSAT mobile number beginning with digit 1.
+
+- b) The routing principles to be used for data transmission to and from ships are as defined in Recommendation X.353.
+
+- c) The procedures to be used on board ships when accessing a subscriber of a PDN should be as similar as possible to the procedures used on PDNs.
+  - d) The Maritime Satellite Service is international in nature and international procedures will be adopted to provide access to this service. For some purposes, a maritime satellite data transmission system can be regarded as analogous to a national network and the ship earth stations as subscribers within that network.
+  - e) The procedures used on board the ship when accessing a subscriber of a PDN should be the same in all coast earth stations.
+- 1.4 The following basic access methods are defined for the Maritime Satellite Data Transmission Service:
+- a) access using the packet mode in accordance with draft Recommendation X.352;
+  - b) access using packet assembly/disassembly facilities (PADS) in accordance with Recommendation X.351.
+- 1.5 Ships may form part of a closed user group (CUG) in accordance with Recommendation X.180. It should be noted that a ship being part of a CUG should be known as such in all coast earth stations.
+
+The International Maritime Satellite Organization (INMARSAT) should be charged with the responsibility of acting as the coordinating Administration (see Recommendation X.180) for ship earth stations wanting to form CUGS. The application from ships to join or cease membership of a CUG should be forwarded through INMARSAT who should then inform the coordinating Administration of the CUG in accordance with Recommendation X.180.
+
+For each CUG the same index identifying the CUG by a calling ship earth station (see Recommendation X.300) should be used in all coast earth stations in order to simplify the calling procedures. The index should be coordinated through INMARSAT.
+
+1.6 Permanent virtual circuits (PVC) would require a permanent circuit between a ship earth station and the coast earth station. The PVC service should not normally be offered to ship earth stations (see also Recommendations X.2 and X.350).
+
+## 2 Procedures for ship originated calls
+
+### 2.1 Access to packet switched PDNs
+
+#### 2.1.1 Calling a subscriber of a PDN
+
+2.1.1.1 The coast earth station through which the call is to be set up is selected by procedures defined within the INMARSAT system.
+
+2.1.1.2 The ship board subscriber should select a prefix followed by the full international number of the called DTE. Hence, the numbering sequence selected by a ship board subscriber will be as shown in Table 1/F.122 or, where an integrated numbering system exists within a country, as shown in Table 2/F.122.
+
+TABLE 1/F.122
+
+|                                   |                                  |
+|-----------------------------------|----------------------------------|
+| 0                                 | Prefix                           |
+| DNIC                              | Data network identification code |
+| N <sub>1</sub> ... N <sub>n</sub> | Network terminal number          |
+
+TABLE 2/F.122
+
+|                                   |                      |
+|-----------------------------------|----------------------|
+| 0                                 | Prefix               |
+| DCC                               | Data country code    |
+| N <sub>1</sub> ... N <sub>n</sub> | National data number |
+
+See also Recommendations X.121 and X.350.
+
+2.1.1.3 The calling DTE address of the ship board DTE should always be inserted and have the following format:
+
+$$TX_1, X_2 \dots X_8 Y$$
+
+where  $TX_1, X_2 \dots X_8$  is the INMARSAT mobile number as defined in Recommendation F.125 and Y is an optional digit identifying a specific DTE on board the ship. If the ship is equipped with only one DTE, the digit Y should be omitted. The calling DTE address should not include the prefix and the DNIC allocated to the ocean area in which the ship earth station is located at the time of the call.
+
+2.1.1.4 Selection of facilities on a call-by-call basis should be in accordance with Recommendations X.25 and X.300. The facilities that may be offered on a call-by-call basis are given in Recommendation X.2. A given facility may not be offered in all coast earth stations.
+
+User facilities that have to be agreed for a contractual period are also listed in Recommendation X.2. The application for a given facility should be made with the Administrations operating coast earth stations providing access to public packet switched data networks. The availability of user facilities on the various coast earth stations should be coordinated and be disseminated to ships by INMARSAT; however, the decision to implement a given user facility should be made by each coast earth station owner.
+
+Further study is required to determine which user facilities and/or other user parameters should be offered on all coast earth stations.
+
+*Note* - Separate provisions apply to closed user groups as described in § 1.5 above.
+
+#### 2.1.2 Use of data transmission prefixes
+
+2.1.2.1 Annex A to Recommendation F.126 defines data transmission prefixes for accessing special terminations. The general called DTE address format when accessing such a termination will be as shown in Table 3/F.122.
+
+TABLE 3/F.122
+
+|                                   |                                                             |
+|-----------------------------------|-------------------------------------------------------------|
+| P <sub>1</sub> P <sub>2</sub>     | Two-digit prefix defined in Annex A to Recommendation F.126 |
+| A <sub>1</sub> ... A <sub>k</sub> | Optional digits                                             |
+
+Optional digits may be a data country code (DCC), a data network identification code (DNIC) or other additional digits.
+
+2.1.2.2 The calling DTE address should have the format defined in § 2.1.1.3 above.
+
+2.1.2.3 Selection of facilities, if required, should be as defined in § 2.1.1.4 above.
+
+2.1.2.4 The use of some prefixes could be barred to some customers.
+
+2.1.2.5 The prefix will be sent on the radio path to the coast earth station but would not be used outside the satellite system. The prefix will be converted at the coast earth station, if required, to the data number associated with the appropriate destination.
+
+#### 2.1.3 Ship-to-ship calls
+
+For ship-to-ship calls the called DTE address should have the composition shown in Table 4/F.122.
+
+TABLE 4/F.122
+
+|   |                                                   |                                                  |
+|---|---------------------------------------------------|--------------------------------------------------|
+| 0 |                                                   | Prefix                                           |
+|   | 111S                                              | DNIC allocated to the Maritime Satellite Service |
+|   | TX <sub>1</sub> X <sub>2</sub> ... X <sub>8</sub> | INMARSAT mobile number                           |
+|   | Y                                                 | Optional digit to designate a particular DTE     |
+
+The digit S determines the ocean area in which the called ship is located. The values for the digit S are given in Recommendation X.121. The digit Y identifies a specific DTE on board the ship.
+
+#### 2.1.4 Call progress signals and diagnostic codes
+
+Call progress signals and diagnostic codes may be received in accordance with § 8.2 of Recommendation X.350.
+
+#### 2.1.5 CCITT standardized services
+
+Ships should have full access to CCITT standardized services offered on public data networks such as Teletex, Videotex, and facsimile in accordance with relevant F and S Series Recommendations.
+
+### 2.2 Access to PADs
+
+2.2.1 Ships with start-stop mode DTEs may be offered access to packet switched public data networks through PADs.
+
+PADs associated with coast earth stations are defined in Recommendation X.351. These PADs are defined in such a way that identical procedures may be used when working towards PADs located at different coast earth stations.
+
+*Note* - Ships may also access a national PAD in a country, but in such cases special procedures only applicable for that PAD would be required. Only PADs designed in accordance with Recommendation X.351 are considered in this Recommendation.
+
+#### 2.2.2 Telephone access procedure
+
+The coast earth station at which the PAD is located is selected in accordance with INMARSAT procedures for telephone calls. The start-stop mode DTE on board the ship would use telephone procedures in order to access a PAD. When the telephone circuit has been established, i.e. when the dial tone is heard, the following digits have to be dialled:
+
+20            Prefix
+
+X<sub>1</sub> X<sub>2</sub>    Digits indicating required data rate
+
+Recommendation X.351 specifies that the following data rates and types of modem for full duplex operation will be supported by the PAD:
+
+- Recommendation V.21, 300 bit/s;
+- Recommendation V.22, 1200 bit/s;
+- Recommendation V.23, 75/1200 bit/s.
+
+The specific modes of operation of the modems are given in Recommendation X.351, § 1.1.
+
+The number to be dialled for each of these data rates is given in Table 5/F.122.
+
+TABLE 5/F.122
+
+| Data rate (bit/s) | Dialling sequence |
+|-------------------|-------------------|
+| 300               | 2002              |
+| 1200              | 2003              |
+| 75/1200           | 2011              |
+
+The PAD may support other data rates on an optional basis. For such data rates the dialling information will be as given in Table 2/X.351.
+
+The dialling sequences 2050 through 2099 are reserved for national use and may be used for access to for example Videotex data bases via the PAD.
+
+#### 2.2.3 *Data access procedures*
+
+The call control procedures to be used during set-up and clearing of the data connection and the data transfer protocol are given in Recommendation X.351.
+
+The basic elements of the procedure are:
+
+First the DTE accesses the PAD by sending a service request signal consisting of the characters “.” (full stop) and “CR” (carriage return) corresponding to the characters 2/14 0/13 of International Alphabet No. 5 (see Recommendation T.50 for a description of International Alphabet No. 5.
+
+The PAD will respond by returning a PAD identification signal, the composition of which is left to the Administration operating the PAD.
+
+The DTE shall then send, as soon as possible, a signal, i.e. a string of characters, called the selection PAD command signal. This signal is composed as shown in Annex A. The purpose of this signal is:
+
+- to provide the PAD with the address of the called DTE; and
+- to provide the PAD with the identity of the calling DTE.
+
+When the call has been extended to the called DTE, the character string COM will be received from the PAD.
+
+At this stage the system enters into the data transfer phase.
+
+The call set-up procedure outlined above may be operated manually or be programmed into the DTE.
+
+During call set-up and during the data transfer phase, the DTE may receive PAD service signals as defined in Recommendation X.28. These signals may indicate various call failures.
+
+Recommendation X.351 also allows other procedures to be used during call set-up. See that Recommendation for further details.
+
+#### 2.2.4 *Standard profile and profile selection*
+
+In order to operate a PAD, a number of PAD parameters must be specified. A general list of PAD parameters is contained in Recommendation X.3.
+
+The PAD defined in Recommendation X.351 offers an initial standard profile with PAD parameter values as given in Table 3/X.351. This standard profile permits a data transfer protocol based on International Alphabet No. 5.
+
+The characters 1/0 (DLE), 1/1 (DC1) and 1/3 (DC3) are used for control purposes and can therefore not be passed transparently through the PAD. The character 1/0 (DLE) is interpreted by the PAD as an escape from the data transfer phase. Therefore, this character is used in order to enable commands to be sent to the PAD. For the various commands that can be used during the data transfer phase, see Recommendation X.28.
+
+The initial standard profile offers the following capabilities:
+
+- by using the character 1/0 (DLE) commands can be sent to the PAD;
+- the PAD can at any time send service signals to the DTE;
+
+- the DTE can use characters in order to indicate when a data packet shall be sent from the PAD into the data network;
+- the DTE may use the characters 1/1 (DC1) and 1/3 (DC3) for flow control.
+
+The profile does not permit the PAD to provide for any editing functions. Characters which are entered into the PAD are not echoed to the DTE. This has been done because the echoed character will be delayed by approximately 0.6 seconds, thus reducing the character rate to less than two characters per second. The echo mode should therefore not be used. If echo is required, it should be generated locally in the DTE.
+
+A transparent profile or any other profile standardized in Recommendation X.28 may be selected as soon as the data transfer phase is entered by procedures defined in Recommendations X.28 and X.351. The transparent profile will allow octets of data to be passed transparently between the two DTEs. When operating in this mode, the on-board DTE cannot recall the PAD, nor can the PAD send any service signals to the on-board DTE. Therefore, a data transfer protocol must exist between the two DTEs for proper call control.
+
+The various PAD parameters which can be selected by the DTE are given in Recommendation X.3. It should be noted that some of these parameters may not be implemented on all PADS.
+
+Since DTEs may treat the parity bit included in the data octets differently when International Alphabet No. 5 is used, Recommendation X.351 specifies the means by which this problem can be resolved.
+
+#### 2.2.5 Clearing of calls
+
+At the end of the call the user at the on-board DTE should make sure that the satellite telephone circuit is properly cleared. The PAD may include provisions for clearing the circuit but this may delay the clearing for several minutes. During this time, the user on-board is still being charged for the use of a maritime satellite telephone circuit.
+
+## 3 Procedures for shore-to-ship calls
+
+### 3.1 Calls to ships with DTEs operating in the packet mode
+
+3.1.1 A subscriber of a PDN calling a ship equipped with DTEs operating in the packet mode will select a numbering sequence as shown in Table 6/F.122.
+
+3.1.2 The numbering sequence requires the subscriber to know the satellite coverage area in which the ship is located in order to select the S digit. The values for the digits are given in Recommendation X.121.
+
+TABLE 6/F.122
+
+|   |     |   |                                                   |                                                     |
+|---|-----|---|---------------------------------------------------|-----------------------------------------------------|
+| P |     |   |                                                   | International prefix (if required)                  |
+|   | 111 |   |                                                   | Martitime data country code                         |
+|   |     | S |                                                   | Ocean area code                                     |
+|   |     |   | TX <sub>1</sub> X <sub>2</sub> ... X <sub>8</sub> | INMARSAT mobile number                              |
+|   |     |   |                                                   | Y      Optional digit to designate a particular DTE |
+
+3.1.3 Facility selection will follow the normal procedures used in the PDN of origin.
+
+3.1.4 The calling subscriber should be aware of the long two-way transmission delay (approximately 0.6 seconds) on the maritime satellite circuit. This implies that acknowledgement signals may be delayed more than for terrestrial connections.
+
+3.1.5 Call progress signals and diagnostic codes may be received in accordance with Recommendation X.350, § 8. 1.
+
+3.1.6 When accessing a ship for CCITT standardized services such as Teletex, Videotex and facsimile, the calling subscriber should make sure before initiating the call that the called ship is equipped with the appropriate termination.
+
+### 3.2 Calls to ships with DTEs operating in the start-stop mode
+
+For further study.
+
+## 4 Group calls
+
+Group calls to ship earth stations are calls comprising a message sent simultaneously to all ships within a predetermined group. The group numbering scheme is given in Annex B of Recommendation F.125.
+
+Group calls using direct access through a PDN will not be permitted.
+
+Other means for setting up group calls through public data networks, e.g. by using a message handling system (MHS), are for further study.
+
+## ANNEX A
+
+(to Recommendation F.122)
+
+### Format of selection PAD command signal for maritime satellite applications
+
+#### A.1 General format
+
+The general format of the selection PAD command signal is given in Recommendation X.28 and is composed as shown in Figure A-1/F.122.
+
+![](b28af4985cdef1e519e3aaf26561dcb3_img.jpg)
+
+Beginning of signal  
+↓
+
+|                         |   |  |   |                         |   |                           |                 |
+|-------------------------|---|--|---|-------------------------|---|---------------------------|-----------------|
+| Facility request signal | , |  | , | Facility request signal | – | Called DTE address signal | (CR)<br>or<br>+ |
+|-------------------------|---|--|---|-------------------------|---|---------------------------|-----------------|
+
+FIGURE A-1/F.122
+
+The character 2/12 (,) is used as a separator between facility request signals and the character 2/13 (–) is used as a separator between the facility request block and the called DTE address signal. The selection PAD command signal is terminated by either of the characters 0/13 (CR) or 2/11 (+).
+
+The facility request block must contain the network user identification (NUI) facility request signal. Other facility request signals are optional.
+
+If the PAD receives a selection PAD command signal with a separator character 2/12 (,) followed by an empty facility request field, the signal will be accepted provided that the other fields of the signal are accepted.
+
+The inclusion of user data in the selection PAD command signals is for further study.
+
+#### A.2 Network user identification (NUI) facility request signal
+
+##### A.2.1 Format of the NUI facility request signal
+
+The NUI facility request signal shall have the format of Figure A-2/F.122 and be sent in the order shown.
+
+Beginning of signal
+
+↓
+
+|   |                                                                 |               |
+|---|-----------------------------------------------------------------|---------------|
+| N | 9 digit INMARSAT mobile number<br>(Recommendations E.215/F.125) | Mnemonic code |
+|---|-----------------------------------------------------------------|---------------|
+
+FIGURE A-2/F.122
+
+N is the character 4/14 (N) of International Alphabet No. 5. The mnemonic code of the NUI facility request signal may consist of 1 to 4 characters in columns 2 to 7 of International Alphabet No. 5, except 2/0 (SP), 7/15 (DEL), 2/13 (-), 2/12 (,) and 2/11 (+).
+
+##### A.2.2 *Validation of the NUI facility request signal*
+
+The coast earth station will check the general authorization of the calling ship for access to the INMARSAT system. Therefore, validation of the NUI facility request signal may be limited to the mnemonic code. However, the possibility of fraudulent calling would be reduced if the ship station identity is also included in the validation.
+
+The ship station identity may also be used for identifying the calling ship for charging purposes, and for insertion of the calling DTE in the call request packet.
+
+#### A.3 *Composition of the called DTE address signal*
+
+#### A.3.1 *Calls to a DTE of a PDN*
+
+The called DTE address signal shall consist of the prefix 0 followed by the full international number of the called DTE. This applies also when the called DTE is located in the same country as the maritime PAD.
+
+#### A.3.2 *Calls to special destinations*
+
+Annex A of Recommendation X.350 defines two-digit prefixes for access to special destinations. For calls to such destinations the called DTE address shall consist of the two-digit prefix, optionally followed by additional digits.
+
+### A.4 *Optional facilities*
+
+Facilities to be offered in a maritime PAD is to be determined by the Administration concerned.
+
+The shipboard DTE may request available facilities in accordance with the procedures given in Recommendation X.28.

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' in a bold, sans-serif font.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.130**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**OPERATIONS AND QUALITY OF SERVICE  
+MOBILE SERVICE**
+
+---
+
+**MARITIME ANSWER - BACK CODES**
+
+**ITU-T Recommendation F.130**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation F.130 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **MARITIME ANSWER-BACK CODES**
+
+The CCITT,
+
+*considering*
+
+(a) that it is technically feasible to interconnect certain radiocommunication systems in the Maritime Mobile Service<sup>1)</sup> with the international telex network in order to provide a radiotelex service between ships and telex subscribers, in accordance with Recommendation F.110;
+
+(b) that Recommendation F.60 specifies the operational provisions for the international telex service, and in particular, for the composition of answer-back codes;
+
+(c) that, since no single Administration is responsible for the allocation of answer-back codes to ships in the way that such codes are administered in individual national telex networks, some rules further to those set down in Recommendation F.60 are desirable, for example to facilitate automatic operation in the ship-to-shore direction and to simplify the handling of inquiries concerning calls to or from ships;
+
+(d) that, to the extent possible, the alphabetic portion of maritime answer-back codes should provide a means for detecting possible mutilation of the numerical portion, particularly in the case of ship-to-shore calls where it may be used for charging and accounting purposes,
+
+*unanimously declares*
+
+that, at least in cases where interconnection with the international telex network is desired, answer-back codes generated by teleprinters (or equivalent terminal devices) on ships shall comply with the following requirements.
+
+**1** Regardless of the transmission medium used (e.g. maritime-mobile satellite, HF "direct printing", VHF), the answer-back code, as printed out for a distant subscriber, shall include the following three components in the order indicated:
+
+- a) the "ship station's number" of 6, 7, 8 or 9 digits (see § 2 below);
+- b) the "ship's (abbreviated) name" of 4 letters (see § 3 below);
+- c) the letter X, preceded by a space, as a "telex network identification code" reserved for mobile stations (see Recommendation F.68).
+
+**2** The 6, 7, 8 or 9 digits of the ship station's number are those allocated by the licensing Administration in accordance with Recommendation F.120 but with the final 3, 2 or 1 zeroes deleted for 6, 7 or 8-digit numbers respectively.
+
+**3** The letters comprising the ship's (abbreviated) name [§ 1b) above] should be chosen with the guidance and under the control of the licensing Administration with a view not only to identifying the ship (or the company, or the fleet, as is most appropriate) in a clear manner for a distant subscriber, but also to providing a means for checking the ship station's number as recorded in the answer-back code. The name should not include shifts, figures or signs. Where a ship has been allocated a 6, 7 or 8-digit number, in principle the ship's (abbreviated) name should not need to be changed when the numbering plan is modified to incorporate 7, 8 or 9-digit numbers.
+
+**4** The series of twenty combinations in International Telegraph Alphabet No. 2 comprising the answer-back code shall be allocated as follows:
+
+---
+
+<sup>1)</sup> As in Recommendation F.110 and F.111, the term Maritime Mobile Service is intended to include also the Maritime Mobile-Satellite Service.
+
+- a) figure-shift, or (if permanently fitted) letter-shift;
+- b) carriage-return;
+- c) line-feed;
+- d) the ship station's number, or (if a letter-shift is fitted in the first position) figure-shift followed by the ship station's number;
+- e) letter-shift;
+- f) space, which should however be omitted if both the ship station's number consists of 8 digits and a letter-shift is fitted in the first position;
+- g) the ship's (abbreviated) name;
+- h) space;
+- i) if necessary, a letter-shift or letter-shifts to bring the total number of combinations in the answer-back code up to twenty;
+- j) the letter X;
+- k) letter-shift (if permanently fitted).
+
+5 The technical requirements for answer-back generators are laid down in Recommendation S.6.
+
+6 In accordance with Recommendation S.6, it is preferred that teleprinters having all 20 positions in the answer-back which are freely assignable should be used in the future, i.e. where the first position is a figure-shift and the last the letter X. In the meantime, teleprinters that have a letter-shift permanently fitted in the first and last positions of the answer-back code may be used where the ship station's number does not exceed 8 digits.

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.131**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**OPERATIONS AND QUALITY OF SERVICE  
+MOBILE SERVICE**
+
+---
+
+**RADIOTELEX SERVICE CODES**
+
+**ITU-T Recommendation F.131**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation F.131 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **RADIOTELEX SERVICE CODES**
+
+The CCITT,
+
+*considering*
+
+(a) that it is technically feasible to interconnect certain radiocommunication systems in the Maritime Mobile Service and the Maritime Mobile-Satellite Service with the international telex network in order to provide a radiotelex service between ships and telex subscribers in accordance with Recommendation F. 110;
+
+(b) that Recommendation F.60 specifies the code expressions used for service correspondence in the international telex service;
+
+(c) that whilst it is desirable for the same service code expressions to be used in the radiotelex service as in the international telex service, because of the nature of the service the reasons for the uses of these codes may vary;
+
+(d) that agreement as to the circumstances when specific codes are used is desirable,
+
+*recommends the following*
+
+(1) In general for shore-to-ship calls the telex service codes specified in Recommendation F.60 should be used. However, the telex service codes listed below should be used by the radiotelex service in the following circumstances:
+
+- ABS** – *Absent subscriber/office closed* (to be used when radio contact cannot be established, i.e. radio equipment is faulty, the ship is outside the coverage area or the terminal is turned off);
+- DER** – *Out of order* (to be used when the radio path and associated handshaking procedure is accomplished normally but the teleprinter fails to respond to the **WRU** signals);
+- NC** – *No circuits* (to be used when congestion occurs in either the network or switching equipment);
+- NP** – *The called party is not or is no longer a subscriber* (to be used when the ship number received is invalid);
+- NA** – *Correspondence with this subscriber is not admitted* (to be used if the ship's number is barred or if unauthorized group calls are attempted);
+- OCC** – *Subscriber engaged* (to be used if the ship station is engaged)
+
+*Note* – See also Recommendation U.61 [1].
+
+(2) For ship-to-shore calls all service codes generated in the international telex service, as specified in Recommendation F.60, should be capable of being returned and presented to the calling ship subscriber.
+
+# **Reference**
+
+- [1] CCITT Recommendation *Detailed requirements to be met in interfacing the international telex network with maritime satellite systems*, Recommendation U.61.

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.19**
+
+(10/1996)
+
+**SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES**
+
+Telegraph service – Operating methods for the  
+international public telegram service
+
+---
+
+**Collection and dissemination of official service  
+information**
+
+ITU-T Recommendation F.19
+
+---
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                        |                 |
+|------------------------------------------------------------------------|-----------------|
+| <b>TELEGRAPH SERVICE</b>                                               |                 |
+| <b>Operating methods for the international public telegram service</b> | <b>F.1–F.19</b> |
+| The gentex network                                                     | F.20–F.29       |
+| Message switching                                                      | F.30–F.39       |
+| The international telemessage service                                  | F.40–F.58       |
+| The international telex service                                        | F.59–F.89       |
+| Statistics and publications on international telegraph services        | F.90–F.99       |
+| Scheduled and leased communication services                            | F.100–F.104     |
+| Phototelegraph service                                                 | F.105–F.109     |
+| <b>MOBILE SERVICE</b>                                                  |                 |
+| Mobile services and multdestination satellite services                 | F.110–F.159     |
+| <b>TELEMATIC SERVICES</b>                                              |                 |
+| Public facsimile service                                               | F.160–F.199     |
+| Teletex service                                                        | F.200–F.299     |
+| Videotex service                                                       | F.300–F.349     |
+| General provisions for telematic services                              | F.350–F.399     |
+| <b>MESSAGE HANDLING SERVICES</b>                                       |                 |
+| <b>DIRECTORY SERVICES</b>                                              |                 |
+| <b>DOCUMENT COMMUNICATION</b>                                          |                 |
+| Document communication                                                 | F.550–F.579     |
+| Programming communication interfaces                                   | F.580–F.599     |
+| <b>DATA TRANSMISSION SERVICES</b>                                      |                 |
+| <b>AUDIOVISUAL SERVICES</b>                                            |                 |
+| <b>ISDN SERVICES</b>                                                   |                 |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                            |                 |
+| <b>HUMAN FACTORS</b>                                                   |                 |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## **ITU-T Recommendation F.19**
+
+## **COLLECTION AND DISSEMINATION OF OFFICIAL SERVICE INFORMATION**
+
+### **Source**
+
+ITU-T Recommendation C.2 was revised by ITU-T Study Group 1 (1993-1996) and approved by WTSC on 18 October 1996. It was then renumbered by ITU-T Study Group 2 (2001-2004) as F.19 on 25 January 2002 without further modifications.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+### INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 2002
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+### CONTENTS
+
+|                                                                    | Page |
+|--------------------------------------------------------------------|------|
+| 1 Service information requirements .....                           | 1    |
+| 2 Collection of data for <i>official</i> service information ..... | 2    |
+| 3 TSB administrative support.....                                  | 2    |
+
+
+
+## **COLLECTION AND DISSEMINATION OF OFFICIAL SERVICE INFORMATION**
+
+*(Approved as ITU-T C.2 in Helsinki, 1993; revised in Geneva, 1996, renumbered as F.19 in 2002)*
+
+The ITU-T,
+
+*considering*
+
+- a) Article 1 of the *Constitution* (Geneva, 1992) and Article 15 of the *Convention* (Geneva, 1992);
+- b) Article 8 of the *International Telecommunication Regulations* (Melbourne, 1988);
+- c) Resolution 21 adopted by the World Telecommunication Standardization Conference (Helsinki, 1993) and the results of the ITU-T studies undertaken pursuant to that Resolution;
+- d) Resolutions 39, 65 and 66 adopted by the Plenipotentiary Conference of the International Telecommunication Union (Kyoto, 1994),
+
+*recognizing*
+
+- a) that the TSB's collection and dissemination of official service information of an administrative, operational, tariff and statistical nature (hereinafter referred to as *official service information*) assists Administrations and ROAs in their efficient administration and provision respectively of international telecommunication services;
+- b) that the *ITU Operational Bulletin* has provided an effective method of promulgating much of this type of information;
+- c) that the decision for the ITU-T to collect and to disseminate official service information should be taken with a view to cost-effectiveness as regards the burden both:
+  - on Administrations and ROAs in providing the information; and
+  - on the TSB in the preparation and dissemination of that information;
+- d) that ROAs also exchange information of an operational nature directly among themselves, and that in some cases (e.g. where many ROAs are affected) some standardization of the content and/or format of the information exchanged may be desirable,
+
+*recommends*
+
+that the following general principles should be applied regarding the collection and dissemination of service information, particularly the *official service information* disseminated by the TSB.
+
+### **1 Service information requirements**
+
+**1.1** Whenever a Study Group identifies a new requirement (or the need for a major change in the existing arrangements) for collection and dissemination of service information:
+
+- a) it should consider whether the relevant ROAs (and/or Administrations) should communicate such service information among themselves directly; or
+- b) if ITU involvement is desired, the Director of the TSB shall be consulted concerning the justification for that involvement, taking into account the perceived market needs, ITU budget considerations, and any other ITU administrative implications before proceeding.
+
+**1.2** In cases a) and b), the requirement should be laid down within ITU-T Recommendations. The relevant Recommendation should specify unambiguously and at least in general terms the nature of the different types of information required. Where appropriate, it may also specify the format, periodicity, entry into effect, and/or procedures for updating the relevant service information.
+
+**1.3** In case a), the information exchanged is not regarded as *official* service information. Nevertheless, in some cases it may be appropriate to specify that each source ROA (or Administration) should supply a copy of the information or a summary of it to the TSB.
+
+1.4 Each Study Group responsible for the maintenance of such Recommendations shall review the relevant provisions at least once towards the end of each period between two WTSCs.
+
+### 2 Collection of data for *official* service information
+
+2.1 The Director of the TSB should request Administrations and/or ROAs to supply official service information, or any changes to previously supplied information, for dissemination in accordance with the provisions of the relevant Recommendations. The form of the request should be designed to minimize the effort required of the Administrations and/or ROAs in providing the information requested.
+
+2.2 Administrations (and/or ROAs) should reply to such requests for information, to the extent practicable, in a timely fashion and in accordance with national arrangements, taking due account of the confidentiality of possibly commercially sensitive information.
+
+2.3 Upon receipt of a request for official service information, Administrations may elect (on a *case-by-case* basis or an *until-further-notice* basis), in accordance with national practice, to make arrangements to collate replies from their ROAs. Any Administration exercising such election shall notify the Director of the TSB. Absent such election and notification, the TSB should expect individual replies from the ROAs. In processing the individual replies, the TSB shall consider them as emanating from an ROA duly authorized by the relevant Member (or its Administration) to offer the relevant telecommunication service(s) to which the request for information pertains.
+
+### 3 TSB administrative support
+
+3.1 The Director of the TSB provides advice and support to the various Study Groups responsible for the Recommendations requiring the collection and dissemination of official service information, in particular as outlined in 1.1, 2.1 and 2.3 above.
+
+3.2 In addition, and in view of the responsibilities vested in his office, the Director makes suitable arrangements:
+
+- a) to establish and to keep up to date, for each Study Group, a list of those Recommendations that require the collection and dissemination of official service information;
+- b) to submit such a list to each Study Group concerned on request, and in any case at least twelve months prior to a WTSC, for possible revision (amendments, additions and/or deletions) in the light of operational experience;
+- c) to ensure that the method of disseminating official service information reflects technical developments in the means of collecting and exchanging such information and that the most appropriate and economic solutions are adopted, while taking due account of the needs of countries where electronic access to ITU databases, for example, is not yet available;
+- d) to establish and to keep up to date on the basis of the responses returned, a list of the relevant service and/or network providers that have provided the official service information and whether their status is that of an Administration, ROA or other entity.
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                              |
+| Series B        | Means of expression: definitions, symbols, classification                                                                      |
+| Series C        | General telecommunication statistics                                                                                           |
+| Series D        | General tariff principles                                                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                              |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                |
+| Series G        | Transmission systems and media, digital systems and networks                                                                   |
+| Series H        | Audiovisual and multimedia systems                                                                                             |
+| Series I        | Integrated services digital network                                                                                            |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                    |
+| Series K        | Protection against interference                                                                                                |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant                                        |
+| Series M        | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                |
+| Series O        | Specifications of measuring equipment                                                                                          |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                   |
+| Series Q        | Switching and signalling                                                                                                       |
+| Series R        | Telegraph transmission                                                                                                         |
+| Series S        | Telegraph services terminal equipment                                                                                          |
+| Series T        | Terminals for telematic services                                                                                               |
+| Series U        | Telegraph switching                                                                                                            |
+| Series V        | Data communication over the telephone network                                                                                  |
+| Series X        | Data networks and open system communications                                                                                   |
+| Series Y        | Global information infrastructure and Internet protocol aspects                                                                |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                           |

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+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**CCITT**
+
+**F.190**
+
+THE INTERNATIONAL  
+TELEGRAPH AND TELEPHONE  
+CONSULTATIVE COMMITTEE
+
+(08/92)
+
+**TELEMATIC, DATA TRANSMISSION,  
+ISDN BROADBAND, UPT  
+AND TELECONFERENCE SERVICES:  
+OPERATIONS AND QUALITY OF SERVICE**
+
+---
+
+**OPERATIONAL PROVISIONS FOR THE  
+INTERNATIONAL FACSIMILE SERVICE  
+BETWEEN PUBLIC BUREAUX AND  
+SUBSCRIBER STATIONS AND VICE VERSA  
+(BUREAUFAX-TELEFAX AND VICE VERSA)**
+
+**Recommendation F.190**
+
+---
+
+![CCITT logo: A globe with the letters CCITT.](84a1d09fb489061482111515543b60dc_img.jpg)
+
+CCITT logo: A globe with the letters CCITT.
+
+Geneva, 1992
+
+# FOREWORD
+
+The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988).
+
+Recommendation F.190 was revised by Study Group I and was approved under the Resolution No. 2 procedure on the 4th of August 1992.
+
+## --- CCITT NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized private operating agency.
+
+
+
+## Recommendation F.190
+
+## OPERATIONAL PROVISIONS FOR THE INTERNATIONAL FACSIMILE SERVICE BETWEEN PUBLIC BUREAUX<sup>1)</sup> AND SUBSCRIBER STATIONS AND VICE VERSA (BUREAUFAX-TELEFAX AND VICE VERSA)
+
+*(revised 1992)*
+
+### 1 General
+
+1.1 Recommendation F.160 lays down general provisions for all forms of international public facsimile services. The specific provisions concerning international public facsimile service between public bureaux (bureaufax) and between subscriber stations are contained in Recommendations F.170, F.171, F.180, F.182 and F.184.
+
+1.2 With a view of increasing the flexibility and range of these facsimile services, this Recommendation deals with the international transmission of facsimile documents:
+
+- a) from a public bureau to a subscriber facsimile station (public-to-private); and
+- b) from a subscriber facsimile station to a public bureau (private-to-public).
+
+1.3 Since the methods of operation do not involve the participation of a public bureau at both ends of the connection, the quality of reproduction and speed of delivery normally available in the conventional bureaufax service may not be attainable.
+
+1.4 In accordance with Recommendation F.170, facsimile terminals should have automatic operation of the called station. The operational procedures applicable in relations between the different types of stations are set out in the relevant Recommendations in the T-Series.
+
+1.5 The relevant tariff provisions may be found in Recommendation D.73.
+
+### 2 “Public-to-private” transmission
+
+2.1 Except where contrary provisions are published by the terminal Administrations concerned, “public-to-private” facsimile transmission is permitted.
+
+2.2 The accepting public bureau should ask the sender of the document or his authorized representative for the following information before accepting the document for transmission:
+
+- a) the CCITT group of the destination subscriber's facsimile terminal;
+- b) the destination facsimile terminal call number.
+
+On accepting the facsimile document, the public bureau can use, if appropriate, the bureaufax transmittal sheet in accordance with Recommendation F.170 and provide the necessary information in the corresponding boxes.
+
+2.3 In those cases where:
+
+- a) the accepting public bureau considers that the quality of the document to be transmitted is unsuitable for satisfactory facsimile transmission; or
+- b) the sender is unsure of the CCITT group of the destination facsimile machine,
+
+---
+
+<sup>1)</sup> Public bureaux may be offices of telecommunication or of postal administrations.
+
+the document will be sent only if the sender accepts the possible risk of non-delivery or of unsatisfactory quality on reception. In effect, the same provisions apply as for **RISQUES EXPEDITEUR** in the bureaufax service (see Recommendation F.170). If b) above applies, or if, after several attempts within a maximum duration of 3 hours from the time of acceptance of the facsimile document, the destination subscriber facsimile terminal cannot be reached, the sender should be given the option of transmission by means of the normal bureaufax service (where available) in accordance with Recommendation F.170, at the tariffs applicable to that service.
+
+*Note* – During an interim period for gaining the greatest possible operational experience, the Administrations should apply the same procedure if they know that the receiving facsimile machine operates automatically.
+
+### 3 “Private-to-public” transmission
+
+3.1 Except where contrary provisions are published by the terminal Administrations concerned, “private-to-public” facsimile transmission is permitted.
+
+3.2 Facsimile documents received by a public bureau from a subscriber station in another country are handled and delivered to the addressee in accordance with appropriate methods laid down by the destination Administration. The provisions of Recommendations F.170, §§ 6.1, 6.3, 6.4 and 6.5 may be applied.
+
+3.3 The sending subscriber shall provide the receiving public bureau with sufficient information for processing his facsimile documents; to that end the subscriber should use a transmittal sheet in accordance with Figure 1/F.190. Administrations should encourage the use of such forms by informing subscribers of their availability. The sending subscriber may insert his logo, company name, etc., in free spaces on the transmittal sheet.
+
+3.4 If the sending subscriber does not use a transmittal sheet as in § 3.3, he shall provide the receiving public bureau with at least the following information:
+
+- a) the call number of his facsimile terminal;
+- b) the number of pages of the document, in accordance with Recommendation F.170, § 3.2.1, item 4);
+- c) the addressee's address, in accordance with Recommendation F.170, § 3.2.1, item 8), as well as the addressee's telephone, telex or teletex numbers if necessary.
+
+It is advisable for the sending subscriber also to give his address, in accordance with Recommendation F.170, § 3.2.1, item 9).
+
+3.5 On receipt of the facsimile document, the receiving bureau should contact the addressee in order to reach agreement on the mode of delivery and the charging.
+
+3.6 The receiving bureau may contact the sending subscriber if the copy received is of unsatisfactory quality.
+
+3.7 In the event of non-delivery owing to incomplete address information or for other reasons (e.g., when the receiving bureau cannot establish contact with the addressee even though the address is complete, or when the document is not collected by the addressee), the receiving bureau may contact the sending subscriber. The facsimile document received and/or other relevant information, should be kept on file in accordance with the national regulations in force.
+
+![Diagram of a transmittal sheet for a private-to-public telefacsimile transmission. The sheet is divided into several boxes for sender and addressee information. Dimensions are given in mm: total height 148, total width 210 (80 + 10 + 90 + 15). Box heights from top to bottom are 45, 15, 42, and 15 mm. The top section contains 'PRIVATE ® PUBLIC' and transmission details. Boxes 1-5 are for sender's telefax, document number, page count, transmission date, and receipt date. Box 6 is for delivery mode instructions. Box 7 is for the addressee's address, and box 8 is for the sender's address.](547f726730e589392f239257a833ede3_img.jpg)
+
+PRIVATE ® PUBLIC
+
+Transmission from a subscriber station to a public bureau
+
+A charge may be collected from the addressee
+
+|                                                                    |                               |
+|--------------------------------------------------------------------|-------------------------------|
+| 1. Sender's telefax No.                                            | 2. Document number            |
+| 3. No. of pages                                                    | 4. Date of transmission       |
+|                                                                    | 5. Date (and time) of receipt |
+| <input type="checkbox"/> 6. Delivery mode and service instructions |                               |
+| 7. Addressee's address (including postal code)                     |                               |
+| 8. Sender's address (including postal code)                        |                               |
+
+Dimensions: 148 (height), 210 a) (width: 80 + 10 + 90 + 15). Box heights: 45, 15, 42, 15.
+
+T0102690-92
+
+Diagram of a transmittal sheet for a private-to-public telefacsimile transmission. The sheet is divided into several boxes for sender and addressee information. Dimensions are given in mm: total height 148, total width 210 (80 + 10 + 90 + 15). Box heights from top to bottom are 45, 15, 42, and 15 mm. The top section contains 'PRIVATE ® PUBLIC' and transmission details. Boxes 1-5 are for sender's telefax, document number, page count, transmission date, and receipt date. Box 6 is for delivery mode instructions. Box 7 is for the addressee's address, and box 8 is for the sender's address.
+
+a) North American standard: 216 mm.
+
+Note 1 – Boxes 2, 5 and 6 are to be filled in by the receiving public bureau.
+
+Note 2 – The information in box 8 (sender) is optional. When given, it must appear in the left-hand part of the transmittal sheet.
+
+Note 3 – The addressee's address should include the telephone, telex or teletex number if necessary.
+
+Note 4 – The number of pages given in box 3 must be in accordance with Recommendation F.170, § 3.2.1, item 4).
+
+Note 5 – Concerning box 6, the following delivery modes may be requested by the addressee, in so far as they are offered by the destination Administration (for definitions, see Annex A to Recommendation F.170):
+
+|          |                                                                       |                                                                |
+|----------|-----------------------------------------------------------------------|----------------------------------------------------------------|
+| <b>A</b> | Ordinary mail                                                         | Courrier ordinaire                                             |
+| <b>B</b> | Special delivery                                                      | Porteur spécial                                                |
+| <b>C</b> | EMS (express mail service)                                            | EMS (service de courrier exprès)                               |
+| <b>D</b> | Counter collection                                                    | Retrait au guichet                                             |
+| <b>E</b> | Counter collection with telephone advice to the indicated call number | Retrait au guichet avec avis téléphonique au numéro indiqué    |
+| <b>F</b> | Telefax (with call number and CCITT group when known)                 | Téléfax (avec numéro d'appel et, s'il est connu, groupe CCITT) |
+| <b>G</b> | Counter collection with telex advice to the indicated call number     | Retrait au guichet avec avis télex au numéro indiqué           |
+| <b>H</b> | Counter collection with teletex advice to the indicated call number   | Retrait au guichet avec avis télétex au numéro indiqué         |
+
+Other modes of delivery may be offered by the destination Administration.
+
+FIGURE 1/F.190  
+**Measurements, locations and designations of the various parts of the transmittal sheet in accordance with § 3.3**

marked/F/T-REC-F.401-199208-I_PDF-E/raw.md

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+
+
+![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with the letters ITU and a lightning bolt.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**CCITT**
+
+**F.401**
+
+THE INTERNATIONAL  
+TELEGRAPH AND TELEPHONE  
+CONSULTATIVE COMMITTEE
+
+(08/92)
+
+**MESSAGE HANDLING SERVICES**
+
+**OPERATIONS AND DEFINITION OF SERVICE**
+
+---
+
+**MESSAGE HANDLING SERVICES:  
+NAMING AND ADDRESSING FOR PUBLIC  
+MESSAGE HANDLING SERVICES**
+
+![CCITT logo: A globe with the letters CCITT.](84a1d09fb489061482111515543b60dc_img.jpg)
+
+CCITT logo: A globe with the letters CCITT.
+
+**Recommendation F.401**
+
+---
+
+# FOREWORD
+
+The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988).
+
+Recommendation F.401 was revised by Study Group I and was approved under the Resolution No. 2 procedure on the 4th of August 1992.
+
+# --- CCITT NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized private operating agency.
+
+# **MESSAGE HANDLING SERVICES: NAMING AND ADDRESSING FOR PUBLIC MESSAGE HANDLING SERVICES**
+
+*(revised, 1992)*
+
+# **CONTENTS**
+
+# *Introduction*
+
+- 1 *Scope*
+- 2 *References*
+- 3 *Definitions*
+- 4 *Abbreviations*
+- 5 *Conventions*
+- 6 *Naming and addressing in message handling*
+  - 6.1 O/R addresses
+  - 6.2 Distribution list names
+  - 6.3 Directory names
+- 7 *Length of attributes*
+- 8 *Principles for the allocation of O/R names and O/R addresses*
+- 9 *Use of O/R names*
+  - 9.1 General
+  - 9.2 Character repertoires
+  - 9.3 Specific rules
+  - 9.4 Support of forms of O/R addresses
+
+*Annex A – List of alpha-2 country codes*
+
+*Annex B – Representation of O/R addresses for human usage*
+
+*Annex C – Format for notification of ADMD names*
+
+# **Introduction**
+
+The establishment in various countries of message handling services in association with public networks creates the need to produce Recommendations covering the aspects of public message handling services. Naming and addressing is a key area for the application and the provision of public message handling services on a global scale.
+
+# 1 Scope
+
+This Recommendation specifies naming and addressing aspects for public message handling services which are described in other Recommendations of the F-Series. It also establishes some principles for the allocation of originator/recipient O/R addresses.
+
+# 2 References
+
+- CCITT Rec. E.164, *Numbering plan for the ISDN era*, 1991.
+- CCITT Rec. F.400, *Message handling services: Message handling system and service overview*, 1992.
+- CCITT Rec. F.410, *Message handling services: The public message transfer service*, 1992.
+- CCITT Rec. F.415, *Message handling services: Intercommunication with public physical delivery services*, 1988.
+- CCITT Rec. F.420, *Message handling services: The public interpersonal messaging service*, 1992.
+- CCITT Rec. F.421, *Message handling services: Intercommunication between the IPM service and the telex service*, 1988.
+- CCITT Rec. F.422, *Message handling services: Intercommunication between the IPM service and the teletex service*, 1988.
+- CCITT Rec. F.423, *Message handling services: Intercommunication between the IPM service and telefax services*, 1992.
+- CCITT Rec. F.435, *Message handling services: electronic data interchange messaging service*, 1991.
+- CCITT Rec. F.440, *Message handling services: The voice messaging service*, 1992.
+- CCITT Rec. F.500, *International public directory services*, 1992.
+- CCITT Rec. T.61 (1992), *Character repertoire and coded character sets for the international teletex service*, 1988.
+- CCITT Rec. X.121, *International numbering plan for public data networks*, 1992.
+- Other CCITT Recs. of the X.400-Series (1993), *Message handling systems*, 1993.
+- CCITT Rec. X.402, *Message handling systems: Overall architecture*, 1993.
+- CCITT Recs. of the X.500-Series, *Directory systems*, 1992.
+- CCITT Rec. X.660<sup>1)</sup>, *Procedures for the operation of OSI registration authorities: General procedures*.
+- ISO 3166 (1988) (plus amendments), *Codes for the representation of names of countries*, 1988.
+
+# 3 Definitions
+
+For the purposes of this Recommendation the definitions given in Recommendation F.400 apply. See also Annex A of Recommendation F.400.
+
+# 4 Abbreviations
+
+|      |                                  |
+|------|----------------------------------|
+| ADMD | Administration management domain |
+| DCC  | Data country code                |
+| DDA  | Domain defined attribute         |
+| DL   | Distribution list                |
+
+---
+
+<sup>1)</sup> Presently at the stage of draft.
+
+|      |                                        |
+|------|----------------------------------------|
+| IA5  | International Alphabet No. 5           |
+| IPM  | Interpersonal messaging                |
+| ITA2 | International Telegraph Alphabet No. 2 |
+| MD   | Management domain                      |
+| MH   | Message handling                       |
+| MHE  | Message handling environment           |
+| MHS  | Message handling system                |
+| MT   | Message transfer                       |
+| O/R  | Originator/recipient                   |
+| OU   | Organizational unit                    |
+| PO   | Post office                            |
+| PD   | Physical delivery                      |
+| PRMD | Private management domain              |
+| PSAP | Presentation service access point      |
+| RPOA | Recognized private operating agency    |
+| UPU  | Universal Postal Union                 |
+
+Abbreviations and labels used in Annex B are explained in the annex itself.
+
+# 5 Conventions
+
+In this Recommendation the expression “Administration” is used for shortness to indicate a telecommunication Administration, a recognized private operating agency (RPOA), and, in the case of intercommunication with public physical delivery service, a postal Administration.
+
+# 6 Naming and addressing in message handling
+
+Naming and addressing in message handling have to ensure that users can define the source and the destination of messages in an unambiguous way. The organizational mapping of message handling systems, and the structure of management domains (see Recommendation F.400), together with a set of naming conventions, are the means to establish a uniform and compatible environment for the exchange of messages between any users of the message handling environment. Only those attributes need appear in an O/R address that are required to reach a recipient.
+
+Names and addresses are allocated by the responsible naming authority. These authorities are asked to notify the Director of the CCITT of the names of their ADMDs and of some additional information (name and address of the public service provider, name of the services, etc.) for subsequent publication in the ITU *Operational Bulletin* (see Annex C for the format of the notification and also Recommendation X.660).
+
+In message handling systems (MHS), the principal entity that requires naming is the user (the originator and the recipient of messages). In addition, distribution lists (DLs) have names for their own identification and use in the context of MHS. Users of MHS and DLs are identified by O/R names. (The prefix “O/R” recognizes the fact that the user can be acting as either the originator or the recipient of a message.) An O/R name comprises a directory name, an O/R address or both. Every user or DL has one or more O/R names.
+
+## 6.1 O/R addresses
+
+An O/R address contains information that enables the MHS to identify a user in order to deliver a message or return a notification. DLs are also identified by an O/R address.
+
+An O/R address is comprised of a set of information called attributes. Recommendation X.402 specifies a set of standard attributes from which O/R addresses can be constructed. Standard attributes, the structure of attribute lists
+
+and their syntax and semantics are defined in Recommendation X.402. In addition to standard attributes, and so as to cater for existing messaging systems, there are domain defined attributes whose syntax and semantics are specified by management domains. They are applicable for an interim period.
+
+Various forms of O/R addresses are defined, each serving its own purpose. These forms and their purpose are as follows:
+
+- *Mnemonic O/R address*: Provides a user friendly means of identifying users in the absence of a directory. It may also be used for identifying a distribution list.
+- *Terminal O/R address*: Provides a means of identifying users with terminals belonging to various networks.
+- *Numeric O/R address*: Provides a means of identifying users with numeric keypads.
+- *Postal O/R address*: Provides a means of identifying originators and recipients of messages and notifications, for physical delivery.
+
+It is up to the management domain concerned to decide which name forms it wants to use. Corresponding parties should be made aware of the applicable name space (i.e. the repertoire of names).
+
+### 6.1.1 *Mnemonic O/R address*
+
+This form of O/R address provides addresses that mnemonically identifies a user or a DL relative to the administration management domain (ADMD) through which the user is accessed. At least one of the conditional attributes following the domain name(s) has to be present. A PRMD name is present only if the user concerned belongs to that domain. If an organizational unit is present, the organization name has to be present as well.
+
+The mnemonic O/R address consists of:
+
+- Country name
+- Administration domain name
+- [Private domain name]
+- [Organization name]
+- [Organizational unit name]
+- [Personal name]
+- [Common name]
+- [[Domain defined attributes ]]
+
+*Note* – Attributes in square brackets are conditional. Double square brackets indicate an attribute not belonging to the standard attribute list and may not be required for global addressing.
+
+### 6.1.2 *Terminal O/R address*
+
+This form of O/R address provides a means for addressing a terminal with its network address, conditionally with the country name, the domain name(s), a terminal identifier, the terminal type and domain defined attributes. If an organizational unit is present, the organization name has to be present as well.
+
+The terminal O/R address consists of:
+
+- [Country name]
+- [Administration domain name]  
+[Private domain name]
+- Network address
+- [Terminal identifier]
+- [Terminal type]
+- [[Domain defined attributes]]
+- {Common name}
+
+- {Organization name}
+- {Organizational unit names}
+- {personal name}
+- {unformatted postal address}
+
+*Note 1* – Attributes in square brackets are conditional. Double square brackets indicate an attribute not belonging to the standard attribute list and may not be required for global addressing.
+
+*Note 2* – Domain defined attributes should be present only if the country name and the Administration management domain name are present.
+
+*Note 3* – Network addresses allocated by a domain need to be unambiguous and thus can only be assigned once. Country name and administration management name attributes have to be present when more than one domain is providing service for the address concerned.
+
+*Note 4* – Attributes in braces are intended to be used for rendering of the address information (making it visible) on the receiving terminal but not for addressing or routing purposes.
+
+The network address is composed of digits from the X.121 numbering plan (including escape codes) or the E.164 numbering plan.
+
+The conditional terminal identifier might be, for example, a telex answerback string or a teletex terminal identifier.
+
+The conditional terminal type might be, for example, a telex, a teletex, a G3 facsimile, a G4 facsimile, an IA5, or a videotex terminal.
+
+### 6.1.3 *Numeric O/R address*
+
+This form of O/R address provides addresses that can be entered from devices equipped only with numeric keypads. It identifies numerically a user relative to the ADM D through which the user is accessed.
+
+The numeric O/R address consists of:
+
+- Country name
+- Administration domain name
+- [Private domain name]
+- Numeric user identifier
+- [[Domain defined attributes]]
+
+*Note 1* – Attributes in square brackets are conditional. Double square brackets indicate an attribute not belonging to the standard attribute list and may not be required for global addressing.
+
+*Note 2* – Numeric values are assumed for all attributes. Countries may be named with DCCs (see Recommendation X.121). An ADM D name would require the allocation of a numeric alias name.
+
+*Note 3* – This form could also be used for a videotex user number.
+
+*Note 4* – The numeric user identifier may use a check digit for validation purposes.
+
+### 6.1.4 *Postal O/R address*
+
+This form of O/R address provides for the identification of a user by means of his postal address, together with the country name(s), and the domain name(s), and the PD service name through which he is accessed.
+
+See also Recommendation F.415.
+
+*Version 1 – Unformatted postal O/R address:*
+
+- Physical delivery country name
+- Country name
+- Administration domain name
+- [Private domain name]
+- [Physical delivery service name]
+- Unformatted postal address
+
+Sufficient address components have to be supplied in the unformatted postal address in order to enable the PD service to route, distribute and deliver the physical message properly.
+
+*Version 2 – Formatted postal O/R address:*
+
+- Physical delivery country name
+- Country name
+- Administration domain name
+- [Private domain name]
+- [Physical delivery service name]
+- Postal code
+- Set of formatted postal address attributes
+
+There is no defined order in the set of formatted postal O/R address attributes. These attributes are:
+
+- *Postal O/R address components:*
+  - a) [Physical delivery personal name]
+  - b) [Physical delivery organization name]
+- *Physical delivery address components:*
+  - a) [Street address]
+  - b) [P.O. box address]
+  - c) [Poste restante address]
+  - d) [Unique postal name]
+- *Physical delivery office address components:*
+  - a) Physical delivery office name
+  - b) [Physical delivery office number]
+  - c) [Local postal attributes]
+- *Other postal address components:*
+  - a) [Extension of postal O/R address components]
+  - b) [Extension of physical delivery address components]
+
+*Note – Attributes in square brackets are conditional.*
+
+Sufficient attributes have to be provided in order to enable the PD service to route, distribute and deliver the physical message properly.
+
+For the description of formatted postal O/R address attributes, see Annex A of Recommendation F.400 and for the length see § 7 of this Recommendation.
+
+## 6.2 *Distribution list names*
+
+In the context of message handling, names of distribution lists (making use of the common name attribute) are used to identify the point of expansion of a message using a distribution list, such list containing a set of O/R addresses or further distribution list names. See Recommendation F.400.
+
+Care should be taken in the choice of distribution list names to ensure that users are aware that they are addressing a distribution list.
+
+*Note* – For naming of distribution lists, the attribute common name may be used. Names of distribution lists should clearly indicate their purpose.
+
+## 6.3 *Directory names*
+
+In the context of message handling, a directory name can be used to retrieve the required O/R address from a directory. See Recommendations F.400 and F.500. The directory may be provided by local functions.
+
+# 7 **Length of attributes**
+
+The coding is specified in the Recommendations of the X.400 series.
+
+The O/R address shall allow the following information:
+
+## - *Country name*
+
+The Alpha-2 country code listed in Annex A or the DCC from Recommendation X.121 can be used as the country name. Maximum 3 characters.
+
+## - *Physical delivery country name*
+
+The same conditions as for *country name* apply.
+
+## - *Physical delivery service name*
+
+Maximum 16 characters.
+
+## - *Administration domain name*
+
+Maximum 16 characters. The Numeric O/R address form assumes allocation of numeric country and administration management domain names.
+
+*Note 1* – If the national option of to use the “space” character for all ADMDs of a country is applied, it should not have any implication on unique global addressing and on routing, accounting or other general international requirements.
+
+*Note 2* – National use of the characters “space” and “0” as ADMD name attributes may have an impact on international messaging. A domain may define the list of ADMD names or PRMD names it wants to accept, depending:
+
+- a) on the naming policy applied; and
+- b) on commercial considerations.
+
+Bilateral agreements between domains may be required for the arrangement chosen.
+
+## - *Private domain name*
+
+Maximum 16 characters.
+
+*Note 3* – Global uniqueness of the private domain name attribute can be assured by allocating values relative to the ADMD name. PRMD names may be the same even when they are used in conjunction with more than one ADMD, because the country name attribute makes the O/R addresses using these attributes unique. National practices may provide for allocation of PRMD names relative to the country name attribute (when registration is performed by the ADMD concerned or by a centralized national registration authority).
+
+## - *Organization name*
+
+Maximum 64 characters.
+
+- *Organizational unit(s)*  
+Maximum 32 characters each.
+- *Personal name*  
+Maximum length is the sum of the maxima of the parts (64 characters).
+  - a) *Surname* – maximum 40 characters.
+  - b) *Given name* – maximum 16 characters.
+  - c) *Initials* (optional) – maximum 5 characters (for further study).
+  - d) *Generation qualifier* (optional) – maximum 3 characters.
+- *Distribution list name*  
+Maximum length of the *common name* applies.
+- *Common name*  
+Maximum 64 characters.
+- *Domain defined attributes*  
+Maximum four separate attributes. Maximum length for “type” 8 and for “value” 128 characters.
+- *Network address*  
+Maximum 14 + 1 digits, including the prefix (see Recommendation X.121).  
+*Note* – The classification and maximum value may change to accommodate other addressing schemes.
+- *Terminal identifier*  
+Maximum 24 characters.
+- *Numeric user identifier*  
+Maximum 32 digits.
+- *Unformatted postal address (version 1)*  
+Up to 6 lines with a maximum of 30 characters in each line (see Note). In the case of transit mail, the last line is reserved for the name of the country of the final physical destination.  
+*Note* – The number of characters specified refers to characters to be printed (including spaces).
+- *Formatted postal address (version 2)*  
+The formatted postal address attributes and their constraints are (for the description of these attributes see Annex A of Recommendation F.400).
+- *Postal O/R address components* (see Note 2)  
+Physical delivery personal name (see Note 3): 30 characters (see Note 1).  
+Physical delivery organization name (see Note 3): 30 characters (see Note 1).
+- *Physical delivery address components* (see Note 2)  
+Street address: 30 characters (see Note 1).  
+P.O. box address: 30 characters (see Note 1).  
+Poste restante address: 30 characters (see Note 1).  
+Unique postal name: 30 characters (see Note 1).
+- *Physical delivery office address components*  
+Physical delivery office name: x number of characters (see Notes 1 and 4).  
+Physical delivery office number: y number of characters (see Notes 1 and 4).  
+Local postal attributes: z number of characters (see Notes 1 and 4).
+
+- *Other postal address components*
+
+Extension of O/R address components (see Note 5): 30 characters (see Note 1).
+
+Extension of physical delivery address components (see Note 6): 30 characters (see Note 1).
+
+The overall constraints are 6 lines of attributes with a maximum of 30 characters in each line (see Note 1). In the case of transit mail, the last line is reserved for the name of the receiving country of the final physical destination.
+
+*Note 1* – The number of characters specified refers to characters to be printed (including spaces).
+
+*Note 2* – At least one of the following attributes should be used.
+
+*Note 3* – Physical delivery personal name and physical delivery organization name are free form names and have different length from personal name and organization name.
+
+*Note 4* – These attributes have to be printed in one line, in some countries together with the postal code. Thus  $x + y + z$  is a maximum of 30 characters including the delimiting spaces and the postal code if printed on the same line.
+
+*Note 5* – May be used to extend the postal O/R address components.
+
+*Note 6* – May be used to extend the physical delivery address components.
+
+# **8 Principles for the allocation of O/R names and O/R addresses**
+
+8.1 The naming authority of the country responsible for administration management domain names will ensure the designation of an unambiguous name to each ADMD of message handling services in that country.
+
+8.2 Each ADMD is responsible for the administration of names of private management domains associated with it.
+
+*Note* – For PRMDs intercommunicating with more than one ADMD, registration with each ADMD will assure uniqueness of O/R addresses used. National practices may provide for registration on a country level.
+
+8.3 Each management domain (MD) is responsible for allocating unambiguous addresses to users below the level of the MD name(s) for the purpose of using message handling services.
+
+8.4 A distribution list shall only be given a name which is clearly indicating to the user its intent. Names or O/R addresses shall only be included in a publicly accessible distribution list when the permission of the owner of the information is given and national rules for security are respected.
+
+# **9 Use of O/R names**
+
+## **9.1 *General***
+
+With the help of O/R names a user can send messages via the MHS. Users may get support from their user agent in the use of O/R names. The latter is a local matter.
+
+## **9.2 *Character repertoires***
+
+The character repertoire allowed in O/R names are either printable, numeric or teletex repertoires (for more detail see Recommendation X.402).
+
+The printable character repertoire is shown in Table 1/F.401.
+
+The numeric character repertoire comprises the digits 0 to 9 and space, and is a subset of the printable character repertoire (see Table 1/F.401).
+
+For the teletex repertoire see Recommendation T.61. In general the teletex repertoire may also be used internationally.
+
+The use of an extended character repertoire within a management domain is a local matter.
+
+TABLE 1/F.401
+
+### **Printable character repertoire for O/R names**
+
+| Designation       | Graphic representation |
+|-------------------|------------------------|
+| Uppercase letters | A, B ..... Z           |
+| Lowercase letters | a, b ..... z           |
+| Digits            | 0, 1 ..... 9           |
+| Space             | (space)                |
+| Apostrophe        | '                      |
+| Left parenthesis  | (                      |
+| Right parenthesis | )                      |
+| Plus sign         | +                      |
+| Comma             | ,                      |
+| Hyphen            | -                      |
+| Full stop         | .                      |
+| Solidus           | /                      |
+| Colon             | :                      |
+| Equals sign       | =                      |
+| Question mark     | ?                      |
+
+*Note* – According to Recommendation X.208, this repertoire is called a printable string type. All these characters are available in ITA2 (as far as letters are concerned, only in uppercase or lowercase).
+
+## 9.3 *Specific rules*
+
+Rules for postal O/R addresses, see §§ 2 and 3 and Recommendation F.415.
+
+Management domains will not allow O/R names, that differ only by the number of “space” characters, either at the beginning or the end of any of their attributes, to identify different users.
+
+Additionally MDs will consider the occurrence of contiguous space characters in an O/R address attribute value to be the same as a single space character.
+
+MDs will not allow O/R names, that differ only by small letter/capital letter distinctions, to identify different users.
+
+## 9.4 *Support of forms of O/R addresses*
+
+Each MHS shall support all the name address forms in the incoming direction for transmitting purposes. It is the decision of the management of a domain which name forms are allocated to the users of that domain. In the outgoing direction the originating domain needs to use the name forms the destination domain applies. The way in which names are inputted by, or presented to, the subscriber is a local matter.
+
+# ANNEX A (to Recommendation F.401)
+
+(This annex does not form an integral part of this Recommendation)
+
+## **List of Alpha-2 country codes**
+
+*Note* – Source: ISO 3166. Current edition (1988) at time of printing. The latest published edition from ISO should be applied.
+
+|                                |    |                              |    |
+|--------------------------------|----|------------------------------|----|
+| Afghanistan                    | AF | Comoros                      | KM |
+| Albania                        | AL | Congo                        | CG |
+| Algeria                        | DZ | Cook Islands                 | CK |
+| American Samoa                 | AS | Costa Rica                   | CR |
+| Andorra                        | AD | Côte d'Ivoire                | CI |
+| Angola                         | AO | Cuba                         | CU |
+| Anguilla                       | AI | Cyprus                       | CY |
+| Antarctica                     | AQ | Czechoslovakia               | CS |
+| Antigua and Barbuda            | AG |                              |    |
+| Argentina                      | AR | Denmark                      | DK |
+| Aruba                          | AW | Djibouti                     | DJ |
+| Australia                      | AU | Dominica                     | DM |
+| Austria                        | AT | Dominican Republic           | DO |
+|                                |    |                              |    |
+| Bahamas                        | BS | East Timor                   | TP |
+| Bahrain                        | BH | Ecuador                      | EC |
+| Bangladesh                     | BD | Egypt                        | EG |
+| Barbados                       | BB | El Salvador                  | SV |
+| Belgium                        | BE | Equatorial Guinea            | GQ |
+| Belize                         | BZ | Ethiopia                     | ET |
+| Benin                          | BJ |                              |    |
+| Bermuda                        | BM | Falkland Islands (Malvinas)  | FK |
+| Bhutan                         | BT | Faeroe Islands               | FO |
+| Bolivia                        | BO | Fiji                         | FJ |
+| Botswana                       | BW | Finland                      | FI |
+| Bouvet Island                  | BV | France                       | FR |
+| Brazil                         | BR | French Guiana                | GF |
+| British Indian Ocean Territory | IO | French Polynesia             | PF |
+| British Virgin Islands         | VG | French Southern Territories  | TF |
+| Brunei Darussalam              | BN |                              |    |
+| Bulgaria                       | BG | Gabon                        | GA |
+| Burkina Faso                   | BF | Gambia                       | GM |
+| Burma                          | BU | Germany, Federal Republic of | DE |
+| Burundi                        | BI | Ghana                        | GH |
+| Byelorussian SR                | BY | Gibraltar                    | GI |
+|                                |    | Greece                       | GR |
+| Cameroon                       | CM | Greenland                    | GL |
+| Canada                         | CA | Grenada                      | GD |
+| Cape Verde                     | CV | Guadeloupe                   | GP |
+| Cayman Islands                 | KY | Guam                         | GU |
+| Central African Republic       | CF | Guatemala                    | GT |
+| Chad                           | TD | Guinea                       | GN |
+| Chile                          | CL | Guinea-Bissau                | GW |
+| China                          | CN | Guyana                       | GY |
+| Christmas Islands              | CX |                              |    |
+| Cocos (Keeling) Islands        | CC | Haiti                        | HT |
+| Colombia                       | CO | Heard and Mc Donald Islands  | HM |
+
+|                                               |    |                                  |    |
+|-----------------------------------------------|----|----------------------------------|----|
+| Honduras                                      | HN | Nigeria                          | NG |
+| Hong Kong                                     | HK | Niue                             | NU |
+| Hungary                                       | HU | Norfolk Island                   | NF |
+|                                               |    | Northern Mariana Islands         | MP |
+| Iceland                                       | IS | Norway                           | NO |
+| India                                         | IN |                                  |    |
+| Indonesia                                     | ID | Oman                             | OM |
+| Iran, Islamic Republic of                     | IR |                                  |    |
+| Iraq                                          | IQ | Pakistan                         | PK |
+| Ireland                                       | IE | Palau                            | PW |
+| Israel                                        | IL | Panama                           | PA |
+| Italy                                         | IT | Papua New Guinea                 | PG |
+|                                               |    | Paraguay                         | PY |
+| Jamaica                                       | JM | Peru                             | PE |
+| Japan                                         | JP | Philippines                      | PH |
+| Jordan                                        | JO | Pitcairn                         | PN |
+|                                               |    | Poland                           | PL |
+| Kampuchea, Democratic                         | KH | Portugal                         | PT |
+| Kenya                                         | KE | Puerto Rico                      | PR |
+| Kiribati                                      | KI |                                  |    |
+| Korea, Democratic People's Republic of        | KP | Qatar                            | QA |
+| Korea, Republic of                            | KR |                                  |    |
+| Kuwait                                        | KW | Réunion                          | RE |
+|                                               |    | Romania                          | RO |
+| Lao People's Democratic Republic              | LA | Rwanda                           | RW |
+| Lebanon                                       | LB |                                  |    |
+| Lesotho                                       | LS | St. Helena                       | SH |
+| Liberia                                       | LR | Saint. Kitts-Nevis               | KN |
+| Libyan Arab Jamahiriya                        | LY | Saint Lucia                      | LC |
+| Liechtenstein                                 | LI | St. Pierre and Miquelon          | PM |
+| Luxembourg                                    | LU | Saint Vincent and the Grenadines | VC |
+|                                               |    | Samoa                            | WS |
+| Macau                                         | MO | San Marino                       | SM |
+| Madagascar                                    | MG | Sao Tome and Principe            | ST |
+| Malawi                                        | MW | Saudi Arabia                     | SA |
+| Malaysia                                      | MY | Senegal                          | SN |
+| Maldives                                      | MV | Seychelles                       | SC |
+| Mali                                          | ML | Sierra Leone                     | SL |
+| Malta                                         | MT | Singapore                        | SG |
+| Marshall Islands                              | MH | Solomon Islands                  | SB |
+| Martinique                                    | MQ | Somalia                          | SO |
+| Mauritania                                    | MR | South Africa                     | ZA |
+| Mauritius                                     | MU | Spain                            | ES |
+| Mexico                                        | MX | Sri Lanka                        | LK |
+| Micronesia                                    | FM | Sudan                            | SD |
+| Monaco                                        | MC | Suriname                         | SR |
+| Mongolia                                      | MN | Svalbard and Jan Mayen Islands   | SJ |
+| Montserrat                                    | MS | Swaziland                        | SZ |
+| Morocco                                       | MA | Sweden                           | SE |
+| Mozambique                                    | MZ | Switzerland                      | CH |
+|                                               |    | Syrian Arab Republic             | SY |
+| Namibia                                       | NA |                                  |    |
+| Nauru                                         | NR | Taiwan, Province of China        | TW |
+| Nepal                                         | NP | Tanzania, United Republic of     | TZ |
+| Netherlands                                   | NL | Thailand                         | TH |
+| Netherlands Antilles                          | AN | Togo                             | TG |
+| Neutral Zone (between Saudia Arabia and Iraq) | NT | Tokelau                          | TK |
+| New Caledonia                                 | NC | Tonga                            | TO |
+| New Zealand                                   | NZ | Trinidad and Tobago              | TT |
+| Nicaragua                                     | NI | Tunisia                          | TN |
+| Niger                                         | NE | Turkey                           | TR |
+
+|                                      |    |                           |    |
+|--------------------------------------|----|---------------------------|----|
+| Turks and Caicos Islands             | TC | Venezuela                 | VE |
+| Tuvalu                               | TV | Viet Nam                  | VN |
+|                                      |    | Virgin Islands, U.S.      | VI |
+| Uganda                               | UG |                           |    |
+| Ukrainian SSR                        | UA | Wallis and Futuna Islands | WF |
+| United Arab Emirates                 | AE | Western Sahara            | EH |
+| United Kingdom                       | GB |                           |    |
+| United States                        | US | Yemen                     | YE |
+| United States Minor Outlying Islands | UM | Yemen, Democratic         | YD |
+| Uruguay                              | UY | Yugoslavia                | YU |
+| USSR                                 | SU |                           |    |
+|                                      |    | Zaire                     | ZR |
+| Vanuatu                              | VU | Zambia                    | ZM |
+| Vatican City State (Holy See)        | VA | Zimbabwe                  | ZW |
+
+# ANNEX B (to Recommendation F.401)
+
+## **Representation of O/R addresses for human usage<sup>1)</sup>**
+
+(This annex does not form an integral part of this Recommendation)
+
+## **B.1      Purpose**
+
+An O/R address consists of a set of attribute values taken from a total of 31 possible attributes. In order to represent visually an address to a human user, and to enable the user to enter the address into a user interface, each attribute value needs to be associated with the correct attribute type. Many of the full attribute types given in Recommendation X.402 are too long for convenient usage on paper or a screen. There is a need for a format which allows attributes to be represented concisely, e.g. on a business card.
+
+This annex specifies how addresses can be expressed concisely using labels to represent the attribute types. There are three categories of attributes: those standard mnemonic attributes which are most likely to be found in O/R addresses represented for human exchange (e.g. on business cards), those used in physical delivery addresses, and other specialized attributes (including domain defined attributes). In order to provide a format which is as concise as possible, many of the labels are single characters. This also makes them less language dependent.
+
+Subsection B.3 specifies the format for the representation of addresses, and § B.4 specifies the characteristics necessary for user interfaces which are intended to be used in conjunction with this format.
+
+## **B.2      Scope**
+
+A labelled format for the communication of O/R addresses to human users is specified. The format consists of a set of pairs of labels and attribute-values. The characteristics of a user interface which are necessary to accept addresses given in this format are also specified.
+
+<sup>1)</sup> This Annex is aligned with ISO/IEC 10021-2, Annex F(DAM) and is referenced in Recommendation X.402
+
+In addition, a self-explanatory format suitable for use where there is more space, e.g. in printed material and in the user interface, is specified.
+
+## B.3 *Format*
+
+### B.3.1 *General*
+
+Some systems are capable of accepting messages when certain optional attributes of the recipient's O/R address [e.g. organizational units (OUs)] are omitted by the originator. In these circumstances it is normally preferable to use the shortest acceptable form of the address when representing the address for human usage.
+
+*Note 1* – OUs should only be used to disambiguate users with the same surname if this cannot be achieved by the use of other name attributes (given name, initials, or generation qualifier). The use of additional OUs for this purpose has the disadvantage that the user's O/R name will change if the naming of the OUs changes, or if the user moves to a different OU.
+
+Where national usage permits a single space value for the ADMD in an address, this may be represented in the address either by omitting the ADMD attribute, or showing the ADMD attribute with no value or the value of a space.
+
+*Note 2* – When sending messages internationally, there may be difficulties in reaching a recipient if a single space ADMD name is specified.
+
+If the attributes of an O/R address include characters from an extended character set, human users who do not normally use the same extended character set may have difficulty representing the O/R address or entering it into their messaging system.
+
+### B.3.2 *Labelled format*
+
+#### B.3.2.1 *Syntax*
+
+O/R addresses in labelled format consist of delimited pairs of labels and values in the syntax <label>“=”<value>. The labels for each attribute are specified in Tables B-1/F.401, B-2/F.401 and B-3/F.401. (The physical delivery attributes in Table B-2/F.401 are included for completeness.) The label and its value are either separated by the character “=”, or by the space between two columns in a table. The value is supplied by the human user and is case insensitive.
+
+If label-value pairs appear in sequence on a line, they are separated by delimiters. The delimiter character may be either “;” or “/”, but only one of these can be used in one O/R address. If the value of any attribute contains the delimiter character, this is represented by a pair of delimiter characters. If the value of the first attribute contains the alternate delimiter character, this is represented by a pair of alternate delimiter characters.
+
+*Note* – When the label-value pairs appear in sequence on a line, the use of upper case for labels and lower case for the values makes the format clearer for the user.
+
+If an identifier is required to preface a labelled address, it is recommended that “X.400” be used.
+
+If an address is entirely composed of attributes contained in Table B-1/F.401, it is recommended that the sequence of attributes in the address be that given in Table B-1/F.401. If this sequence is incompatible with normal cultural conventions, an alternative sequence may be adopted for representations of addresses which are primarily intended for use within that culture.
+
+TABLE B-1/F.401
+
+##### **Standard attributes of the mnemonic address form**
+
+| Attribute type                        | Abbreviation | Label<br>(where necessary) |
+|---------------------------------------|--------------|----------------------------|
+| Given name                            | Given name   | G                          |
+| Initials                              | Initials     | I                          |
+| Surname                               | Surname      | S                          |
+| Generation qualifier                  | Generation   | Q                          |
+| Common name                           | Common name  | CN                         |
+| Organization                          | Organization | O                          |
+| Organizational unit 1                 | Org.Unit.1   | OU1                        |
+| Organizational unit 2                 | Org.Unit.2   | OU2                        |
+| Organizational unit 3                 | Org.Unit.3   | OU3                        |
+| Organizational unit 4                 | Org.Unit.4   | OU4                        |
+| Private management domain name        | PRMD         | P                          |
+| Administration management domain name | ADMD         | A                          |
+| Country                               | Country      | C                          |
+
+TABLE B-2/F.401
+
+###### **Physical delivery attributes**
+
+| Attribute type                                    | Abbreviation     | Label<br>(where necessary) |
+|---------------------------------------------------|------------------|----------------------------|
+| Physical delivery personal name                   | PD-PN            | PD-PN                      |
+| Extension of postal O/R address components        | PD-ext.delivery  | PD-EA                      |
+| Extension of physical delivery address components | PD-ext.address   | PD-ED                      |
+| Physical delivery office number                   | PD-office number | PD-OFN                     |
+| Physical delivery office name                     | PD-office        | PD-OF                      |
+| Physical delivery organization name               | PD-O             | PD-O                       |
+| Street address                                    | PD-street        | PD-S                       |
+| Unformatted postal address                        | PD-address       | PD-A                       |
+| Unique postal name                                | PD-unique        | PD-U                       |
+| Local postal attributes                           | PD-local         | PD-L                       |
+| Postal restante address                           | PD-restante      | PD-R                       |
+| Post office box address                           | PD-box           | PD-B                       |
+| Postal code                                       | PD-code          | PD-PC                      |
+| Physical delivery service name                    | PD-service       | PD-SN                      |
+| Physical delivery country name                    | PD-C             | PD-C                       |
+
+TABLE B-3/F.401
+
+###### **Other attributes**
+
+| Attribute type           | Abbreviation  | Label<br>(where necessary) |
+|--------------------------|---------------|----------------------------|
+| X.121 network address    | X.121         | X.121                      |
+| E.164 network address    | E.164         | E.164                      |
+| PSAP network address     | PSAP          | PSAP                       |
+| User agent numeric ID    | N-ID          | N-ID                       |
+| Terminal identifier      | T-ID          | T-ID                       |
+| Terminal type            | T-TY          | T-TY                       |
+| Domain defined attribute | DDA:<type> a) | DDA:<type> a)              |
+
+a) The notation <type> identifies the type of domain defined attribute.
+
+*Example* – X.400: G=john; S=smith; O=a bank ltd; P=abl; A=snomail; C=aq
+
+This address may also be laid out as a table:
+
+G John  
+ S Smith  
+ O A Bank Ltd  
+ P ABL  
+ A Snomail  
+ C AQ
+
+#### B.3.2.2 Terminal type
+
+There are currently six terminal types, and if international consistency is required, the following specific abbreviations should be used to represent the values for these types: tlx, ttx, g3fax, g4fax, ia5 and vtx.
+
+#### B.3.2.3 Domain defined attribute
+
+The label for a domain defined attribute (DDA) consists of “DDA:” followed by the DDA type. If an address includes more than one DDA of the same type, it is assumed that the DDAs are intended to be processed in the sequence in which they are represented.
+
+*Example* – DDA:RFC-822=fred(a)widget.co.uk; O=gateway; P=abc; C=gb
+
+If the <type> of a DDA type includes the character “=”, it is represented by “==”.
+
+### B.3.3 Self-explanatory format
+
+The self-explanatory format may be used when space is available. It consists of a list of the attribute types, either in full or abbreviated. The attribute types or abbreviations may be in any language, but each attribute type or abbreviation in Table B-1/F.401 is followed by the specified label. If English language abbreviations are used, they should be those given in Tables B-1/F.401, B-2/F.401 and B-3/F.401.
+
+If an address is entirely composed of attributes contained in Table B-1/F.401, it is recommended that the sequence of attributes in the address is that given in Table B-1/F.401. If this sequence is incompatible with normal cultural conventions, an alternative sequence may be adopted for representations of addresses which are primarily intended for use within that culture.
+
+#### *Example 1 – Using attribute types in the Norwegian language*
+
+|                           |           |
+|---------------------------|-----------|
+| Fornavn (G)               | Per       |
+| Etternavn (S)             | Hansen    |
+| Organisasjon (O)          | Teledir   |
+| Organisasjonsenhet (OU1)  | Forskning |
+| Privat domene (P)         | Tele      |
+| Administrasjonsdomene (A) | Telemax   |
+| Land (C)                  | NO        |
+
+#### *Example 2 – Using attribute types and abbreviations in the English language*
+
+|                  |            |
+|------------------|------------|
+| Given name (G)   | John       |
+| Surname (S)      | Smith      |
+| Organization (O) | A Bank Ltd |
+| Org. Unit (OU1)  | IT Dept    |
+| Org. Unit (OU2)  | MSG Group  |
+| PRMD (P)         | ABL        |
+| ADMD (A)         | Snomail    |
+| Country (C)      | AQ         |
+
+## B.4 *User interface*
+
+This subsection specifies the characteristics of a user interface which are necessary to enable a user to input O/R addresses represented in either of the formats specified in § B.3.
+
+It is necessary for the user interface to be able to accept any valid combination of attributes from Tables B-1/F.401, B-2/F.401 and B-3/F.401.
+
+If the user interface lists the attributes given in Table B-1/F.401, it is recommended that either the sequence used in Table B-1/F.401 should be used, or if this sequence is incompatible with normal cultural conventions, an alternative sequence may be adopted for representations of addresses which are primarily intended for use within that culture.
+
+If the user omits the ADMD attribute, or omits the value for the ADMD attribute, the ADMD value to be used is a single space provided that the country specified in the O/R address permits use of the single space value for ADMDS.
+
+Where an interface accepts an O/R address as a single string (e.g. in a command line interface), it is necessary to accept any valid labelled format address allowing the user to enter either of the valid delimiters. The interface should not require the attributes to be specified in any particular order.
+
+*Note* – For some existing command line interfaces, it may be necessary to enclose the whole labelled format address in quotes.
+
+If any other type of interface is provided (e.g. a prompting or form-fill interface), it is necessary to provide a means which enables the user to easily associate the identity of each attribute with the labels specified in Tables B-1/F.401, B-2/F.401 and B-3/F.401.
+
+*Note 1* – One way to associate the identity of each attribute with the labels is to follow the name or abbreviation for each attribute with the label in brackets, for example:
+
+|                          |
+|--------------------------|
+| Given name (G)           |
+| Initials (I)             |
+| Surname (S)              |
+| Generation qualifier (Q) |
+| Common name (CN)         |
+| Organization (O)         |
+
+Organizational unit 1 (OU1)  
+Organizational unit 2 (OU2)  
+Organizational unit 3 (OU3)  
+Organizational unit 4 (OU4)  
+Private management domain name (P)  
+Administration management domain name (A)  
+Country (C)
+
+*Note 2* – Many users may have difficulty copying an address presented as a table (either in labelled or self-explanatory format) into a command line interface which uses delimiters.
+
+*Note 3* – For form-fill style interfaces, user performance will be optimized when the interface most closely resembles the format of the supplied address with the same sequence of attributes using the same attribute types or labels.
+
+### B.4.1 *Examples of application*
+
+*Example 1* – The Norwegian user of a command line interface receives a business card containing the following O/R address:
+
+G=john; S=smith; O=a bank ltd; P=abl; A=snomail; C=aq
+
+The command line interface enables the user to type in the address exactly as presented on the card.
+
+*Example 2* – The Norwegian user of a form-fill interface receives the same business card. The form on the screen includes the following field names:
+
+Fornavn (G)  
+Etternavn (S)  
+Organisasjon (O)  
+Privat domene (P)  
+Administrasjonsdomene (A)  
+Land (C)
+
+The user is able to fill in the form by associating the single letter labels on the business card with the same labels in brackets after the Norwegian names of the attributes on the screen. (For form-fill input, the delimiters are not used.)
+
+*Example 3* – The English speaking user of a command line interface receives a document quoting the following O/R address:
+
+|                           |           |
+|---------------------------|-----------|
+| Fornavn (G)               | Per       |
+| Etternavn (S)             | Hansen    |
+| Organisasjon (O)          | Teledir   |
+| Organisasjonsenhet (OU1)  | Forskning |
+| Privat domene (P)         | Tele      |
+| Administrasjonsdomene (A) | Telemax   |
+| Land (C)                  | NO        |
+
+The user has been trained how to use the interface, and can correctly enter the address either as:
+
+g=per;s=hansen;o=teledir;ou1=forskning;p=tele;a=telemax;c=no
+
+or as:
+
+g=per/s=hansen/o=teledir/ou1=forskning/p=tele/a=telemax/c=no
+
+(The input supplied by the human user is not case sensitive.)
+
+# ANNEX C (to Recommendation F.401)
+
+## **Format for notification of ADMD names**
+
+(This annex does not form an integral part of this Recommendation)
+
+<Address of the organization providing the information>
+
+To be sent to: Director  
+CCITT  
+Place des Nations  
+1211 GENEVA 20  
+Switzerland
+
+## C.1 *Notification of X.400 ADMD name*
+
+The information is provided for the purpose of making ADMD names available for reference, and for potential service providers to obtain contact addresses for interconnection arrangements on a bilateral basis.
+
+| Provision of X.400 message handling services          |     |    |                  |
+|-------------------------------------------------------|-----|----|------------------|
+| Service name (MT):                                    |     |    | } As appropriate |
+| Service name (IPM):                                   |     |    |                  |
+| Service name (...):                                   |     |    |                  |
+| ADMD name:                                            |     |    |                  |
+| Country <sup>a)</sup>                                 |     |    |                  |
+| Contact address:<br>(Postal address)                  |     |    |                  |
+| Telephone:                                            |     |    |                  |
+| Telefax:                                              |     |    |                  |
+| Telex:                                                |     |    |                  |
+| X.400:                                                |     |    |                  |
+| HELPDESK<br>available? <sup>b)</sup><br>(check one)   | Yes | No |                  |
+| AUTOANSWER<br>available? <sup>b)</sup><br>(check one) | Yes | No |                  |
+
+<sup>a)</sup> Use Alpha-2 country codes of Annex A.
+
+<sup>b)</sup> It is proposed to provide two O/R-addresses, namely HELPDESK and AUTOANSWER (together with no other attributes than country and domain names).
+
+*Example 1* – S=helpdesk; A=arcom; C=ch;
+
+*Example 2* – S=autoanswer; A=dbp; C=de
+
+*Note* – National practices may impose coordination before sending notification to the ITU.

marked/F/T-REC-F.421-198811-I_PDF-E/raw.md

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. A lightning bolt symbol is positioned to the right of the globe.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.421**
+
+# **OPERATIONS AND QUALITY OF SERVICE MESSAGE HANDLING SERVICES** ---
+
+## **MESSAGE HANDLING SERVICES: INTERCOMMUNICATION BETWEEN THE IPM SERVICE AND THE TELEX SERVICE**
+
+**ITU-T Recommendation F.421**
+
+(Extract from the *Blue Book*)
+
+---
+
+## NOTES
+
+1 ITU-T Recommendation F.421 was published in Fascicle II.6 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+### Recommendation F.421<sup>1)</sup>
+
+## MESSAGE HANDLING SERVICES: INTERCOMMUNICATION BETWEEN THE IPM SERVICE AND THE TELEX SERVICE
+
+The establishment in various countries of message handling service in association with public networks creates the need to produce Recommendations covering the aspects of public message handling services.
+
+The CCITT,
+
+*considering*
+
+- (a) the need for public message handling services;
+- (b) the strategic and commercial importance of standardization of message handling services;
+- (c) the urgent need for intercommunication arrangements for existing telematic services, and other services with public message handling services;
+- (d) the need for a clear distinction between the responsibilities to be allocated to service providers and those of subscribers and/or users;
+- (e) the need for establishing international compatibility between different messaging systems;
+- (f) the growth of the installed base of terminals and personal computers with the ability to access message handling systems;
+- (g) that several F-series Recommendations describe public message handling services;
+- (h) that certain X, T and U-series Recommendations cover relevant aspects of systems used for the provision of messaging services;
+- (i) that Recommendations F.60 and F.69 define the service requirements for the telex service;
+- (j) that Recommendation F.72 defines international telex store-and-forward;
+- (k) that the U-series Recommendations define the technical requirements for the telex service;
+- (l) that Recommendation U.204 defines the technical requirements for the intercommunication between the IPM service and the telex service;
+
+*unanimously declares*
+
+that operational procedures for intercommunication between the public interpersonal messaging service and the telex service shall be in accordance with this Recommendation.
+
+## CONTENTS
+
+- 1 *Scope*
+- 2 *Introduction*
+- 3 *Service outline*
+- 4 *Operational procedures*
+  - 4.1 IPM service to telex service direction
+  - 4.2 Telex service to IPM service direction
+  - 4.3 Construction of the IP-message
+
+---
+
+<sup>1)</sup> This Recommendation is the same as Recommendation F.75 of which only the title appears in Fascicle II.4.
+
+*Annex A* – Abbreviations
+
+*Annex B* – Actions to be taken by the PTLXAU/examples
+
+*Annex C* – IPM message to telex
+
+*Annex D* – Telex message to IPM
+
+## 1 Scope
+
+1.1 This Recommendation describes the general, operational and service procedures for the provision of intercommunication between the public interpersonal messaging service and the telex service.
+
+1.2 The intercommunication is based on store-and-forward principles which allow users of one service to exchange messages with the users of the other service.
+
+# 2 Introduction
+
+The IPM service is a messaging service which may be provided on a variety of networks and allows several forms of addresses, whereas the telex service provides direct connection between subscribers in the telex network.
+
+Therefore, to match dissimilar characteristics of the two services, it is necessary to provide intercommunication via a public telex access unit (PTLXAU). In both IPM service to telex service, and telex service to IPM service directions, the complete message is deposited in the PTLXAU for onward transmission.
+
+In general the selection procedures for the telex subscriber will be two-stage; however, where the destination IPM service user is assigned a numeric address that is part of the national telex numbering plan of the destination country, one-stage selection procedures may be used.
+
+## 3 Service outline
+
+3.1 Communication between subscribers of the telex service and the IPM service is on store-and-forward basis; thus conversational mode interworking between users is not applicable.
+
+3.2 Public access to the IPM service for telex subscribers and delivery of messages to telex subscribers from IPM service users is provided by means of a PTLXAU.
+
+3.3 The PTLXAU belongs to the IPM service.
+
+3.4 In the IPM service to telex service direction, the IPM service retains the responsibility for the message until delivery to the telex subscriber has been completed.
+
+3.5 In the telex service to IPM service direction, the IPM service is responsible for the delivery of the message to the IPM service user, once the input is completed under normal conditions.
+
+3.6 In both IPM service to telex service direction and telex service to IPM service direction, the international connection should be via the international telex network, as shown in Figure 1/F.421.
+
+![Diagram illustrating the model for service intercommunication between Country A and Country B. Country A contains a 'Telex service' oval with two 'Telex network' boxes separated by a dashed vertical line labeled 'International boundary'. Country B contains an 'IPM service' oval with a 'PTLXAU' box. A solid horizontal line connects the second 'Telex network' in Country A to the 'PTLXAU' in Country B. A small text 'CCITT - 0100740-89' is at the bottom right.](8e85c350ee10ead46f7834b148b8b7d3_img.jpg)
+
+The diagram shows two countries, Country A and Country B, separated by an international boundary. Country A contains a 'Telex service' represented by an oval enclosing two 'Telex network' boxes. The international boundary is a dashed vertical line between these two boxes. Country B contains an 'IPM service' represented by an oval enclosing a 'PTLXAU' box. A solid horizontal line connects the second 'Telex network' in Country A to the 'PTLXAU' in Country B. The text 'CCITT - 0100740-89' is located at the bottom right of the diagram.
+
+Diagram illustrating the model for service intercommunication between Country A and Country B. Country A contains a 'Telex service' oval with two 'Telex network' boxes separated by a dashed vertical line labeled 'International boundary'. Country B contains an 'IPM service' oval with a 'PTLXAU' box. A solid horizontal line connects the second 'Telex network' in Country A to the 'PTLXAU' in Country B. A small text 'CCITT - 0100740-89' is at the bottom right.
+
+FIGURE 1/F.421
+
+Model for service intercommunication
+
+3.7 Where two Administrations offer an IPM service, the international boundary may be placed within the IPM service by bilateral agreement. In this configuration, however, international telex connections should continue to be established via the international telex network.
+
+## 4 Operational procedures
+
+### 4.1 *IPM service to telex service direction*
+
+4.1.1 Messages from an IPM service user to a telex subscriber are sent as normal IP-message with the appropriate IPM elements of service, in accordance with Recommendation F.420.
+
+4.1.2 When a message is received by the PTLXAU, the message content will be converted into the format and character repertoire defined for the telex service. This may result in loss of information if the IPM service user does not conform to these defined rules.
+
+*Note* – The conversion process may take place in the message transfer system (MTS) associated with the PTLXAU.
+
+4.1.3 The PTLXAU shall be responsible for the action to be taken for IPM elements of service received in accordance with Recommendation F.420. Annex B shows examples of IPM elements of service together with proposed actions to be taken by the PTLXAU.
+
+4.1.4 Call establishment by and delivery of the message to the telex subscriber should be in accordance with Recommendations F.72 and U.204.
+
+4.1.5 The IP-message sent to the called telex subscriber shall be preceded by a PTLXAU identification. The content of this identification is a national matter but should include the service code “CI”, the code expression “IPM”, and the telex network identification code in accordance with Recommendation F.69, e.g. “CI → IPM → CH”.
+
+4.1.6 A general layout of an IP-message delivered to the telex service is shown in Annex C.
+
+4.1.7 The elements of service related to the IP-message heading shall be converted into printable text. The language of this text is a national matter. The PTLXAU shall transmit the originator O/R address to the called telex subscriber in the form necessary for recall, in accordance with the indications of Table 2/F.421 (see example in Annex C).
+
+4.1.8 In order to help the telex recipients to recall the originator, the PTLXAU could transmit, as the first element of the message heading, some information as guidance. The contents of this field is a national matter, but when used should be called “FOR RECALL” (see Annex C).
+
+4.1.9 Upon delivery of the message to the telex subscriber, a delivery notification should be sent back to the originating IPM service user if requested. In the event of non-delivery of the message to the telex subscriber, a non-delivery notification shall be sent back to the IPM service user (unless the IPM user has requested prevention of non-delivery notification).
+
+### 4.2 *Telex service to IPM service direction*
+
+In this direction, Administrations may implement either or both one-stage and two-stage call set-up procedures.
+
+#### 4.2.1 *One-stage selection*
+
+4.2.1.1 Where one-stage call set-up procedures are used, the number assigned to a user in the IPM service must appear to be part of the national telex numbering plan.
+
+4.2.1.2 The length of the number assigned to the IPM service user shall be in accordance with the relevant U-series signalling Recommendations.
+
+4.2.1.3 The procedures for message transfer within the IPM service, e.g. mapping of the assigned number to an O/R address, are a national matter and not covered by this Recommendation.
+
+4.2.1.4 The call shall be established using normal telex call set-up procedures.
+
+4.2.1.5 The telex number received by the PTLXAU from the telex network shall be verified by the IPM service as being proper to a registered IPM service user. If the verification fails:
+
+- a) where the PTLXAU is provided by the Administration which also provides all or part of the telex network, the service signal NP may be returned;
+- b) where the PTLXAU is not provided by the Administration which also provides all or part of the telex network, the procedures to be applied shall be in accordance with Recommendation F.74.
+
+4.2.1.6 The answerback returned to the calling telex subscriber at call establishment and also during the text input stage shall contain the national telex number assigned to the IPM service user.
+
+4.2.1.7 The call shall be cleared using normal telex call clearing procedures.
+
+4.2.1.8 When the message cannot be delivered to the IPM service user, a non-delivery notification shall be returned to the telex subscriber. The procedures for establishing the calling telex address are specified in Recommendation U.204.
+
+4.2.1.9 The non-delivery notification returned to the originating telex subscriber should contain a reference consisting of the telex address of the IPM service user and time and date of submission to the PTLXAU.
+
+4.2.1.10 The action to be taken when a non-delivery notification cannot be returned to the calling telex subscriber is for further study.
+
+4.2.1.11 The format of notifications and the procedures for their delivery should be in accordance with Recommendation U.204.
+
+4.2.1.12 The use of IPM elements of service by the telex subscriber is for further study.
+
+#### 4.2.2 *Two-stage selection*
+
+4.2.2.1 The telex subscribers shall use normal telex call procedures to access the PTLXAU which is allocated a telex number that is part of the national telex numbering plan of the country in which the PTLXAU is located.
+
+4.2.2.2 Procedures for access to the PTLXAU shall follow Recommendation U.204.
+
+4.2.2.3 A service identifier may be input before the O/R address(es) of the first message. It may allow the Administrations to provide intercommunication with several services through only one PTLXAU (see Tables 1/F.421, 3/F.421 and Annex D).
+
+4.2.2.4 The PTLXAU shall be able to accommodate the following O/R address forms:
+
+- Mnemonic O/R address;
+- Terminal O/R address;
+- Numeric O/R address;
+
+as specified in Recommendation F.401. The O/R address should be input in accordance with the requirements of Recommendation U.204.
+
+It is the responsibility of the originating telex subscriber to be aware of the required attributes specific to the domain of the called IPM service user. Each attribute of the O/R address shall be identified and delimited. The complete O/R address shall be terminated with an end-of-address (EOA) indicator.
+
+The structure of the service identifier and the address input is shown in Table 1/F.421.
+
+Each attribute of the address structure shall be contained in one line.
+
+Each address attribute and the service shall be identified by a code expression according to Tables 2/F.421 and 3/F.421.
+
+4.2.2.5 Under normal conditions, the message input will be terminated by an end of message (EOM) or an end of transmission (EOT) signal. In case where no EOM or EOT signal is received, the PTLXAU shall forward any input received prior to call disconnect with the added text "THIS MESSAGE MAY BE INCOMPLETE". Annex D shows a general layout applicable in case of submission of message(s) to the PTLXAU by the telex subscriber.
+
+4.2.2.6 Except as defined in 4.2.2.5 above, the action to be taken when abnormal conditions are encountered during message input shall be in accordance with Recommendation U.204.
+
+TABLE 1/F.421
+
+#### **Telex service to IPM service address structure**
+
+|                                       |
+|---------------------------------------|
+| Service identifier                    |
+| Address attribute identifier <value>  |
+| .                                     |
+| .                                     |
+| .                                     |
+| Address attribute identifier <value>  |
+| End of single O/R address (+)         |
+| [Next O/R address(es)]                |
+| [Request for IPM elements of service] |
+| End of address(es) (BT)               |
+| [Request for delivery notification]   |
+
+*Note – [ ] indicates optional attributes.*
+
+TABLE 2/F.421
+
+#### **Code expressions for address attribute identifiers**
+
+| Address attribute                              | Format        |
+|------------------------------------------------|---------------|
+| Country name                                   | CTN → <value> |
+| Administration domain name                     | ADM → <value> |
+| Private domain name                            | PRI → <value> |
+| Organization name                              | ORG → <value> |
+| Organisation unit name(s)                      | OUN → <value> |
+| Personal name                                  |               |
+| – Surname                                      | SUR → <value> |
+| – Given name                                   | GIV → <value> |
+| – Initials                                     | INI → <value> |
+| – Generation qualifier                         | GEN → <value> |
+| – Common name                                  | COM → <value> |
+| Numeric user identifier                        | NUS → <value> |
+| Terminal type and network address<br>for telex |               |
+| teletex                                        | TLX → <value> |
+| fascimile                                      | TTX → <value> |
+| videotex                                       | FAX → <value> |
+| Domain defined attribute(s)                    | VTX → <value> |
+| – Type                                         | DDT → <value> |
+| – Value                                        | DDV → <value> |
+
+*Note 1 – The symbol → equals a space .*
+
+*Note 2 – Allowed attribute values are specified in Recommendation F.401.*
+
+TABLE 3/F.421
+
+##### **Code expression for the service identifier**
+
+| Service                         | Format |
+|---------------------------------|--------|
+| Interpersonal messaging service | IPM    |
+
+4.2.2.7 During the input stage of the address, the PTLXAU shall validate, as a minimum, the following O/R address formats, as specified by the domain:
+
+- The existence of mandatory attributes.
+- The existence of non-allowed attributes.
+- The minimum and maximum allowed number of characters in each attribute.
+- The existence of non-allowed characters in an attribute.
+
+Where applicable, the existence/non-existence of non-significant character(s) preceding or following the attribute values shall not prevent validation.
+
+Despite the acceptance by the PTLXAU of the submitted O/R address, there is no guarantee that the message will be subsequently delivered and, in this case, the originating telex subscriber will be charged for a message which was not delivered. It is therefore desirable that a means of verifying the existence of the O/R address be provided and the method of achieving this is left for further study.
+
+4.2.2.8 The service principles for delivery and non-delivery notifications should be in accordance with Recommendation F.72. The format of the notification messages is defined in Recommendation U.204. Delivery notification may be requested as a code expression following the end of address signal.
+
+### 4.3 *Construction of the IP-message*
+
+The message received by the PTLXAU shall be delivered to the IPM user(s) in accordance with following rules.
+
+#### 4.3.1 *P2 body part*
+
+The received message, excluding the recipient address(es), shall form the body of the IP-message. All the received characters shall be delivered except the WRU signals.
+
+#### 4.3.2 *Recipient O/R address*
+
+All recognized O/R addresses shall be assumed as primary recipients. By default, these primary recipients will not be disclosed to each other.
+
+#### 4.3.3 *Originator indication*
+
+The calling telex subscriber address shall be converted by the PTLXAU into the format of a terminal O/R address and shall be placed in the originator indication element of service field.
+
+#### 4.3.4 *Subject indication*
+
+The PTLXAU shall generate the element of service which will cause TELEX to appear in the subject indication element of service field.
+
+#### 4.3.5 *IP-message identification*
+
+The content of the message reference information returned to the calling telex subscriber shall also be used as the unique identifier in the IP-message identification element of service field.
+
+#### 4.3.6 *Grade of delivery selection*
+
+The PTLXAU shall set the grade of delivery selection element of service to the value URGENT.
+
+#### 4.3.7 *Conversion prohibition in case of loss of information*
+
+The use of the element of service – conversion prohibition in case of loss of information – is for further study.
+
+#### 4.3.8 *Disclosure of other recipients*
+
+This element of service shall be set by the PTLXAU when the originating telex subscriber requests the disclosure of other recipients. The procedures for requesting this disclosure are defined in Recommendation U.204.
+
+#### 4.3.9 *Deferred delivery*
+
+This element of service shall be set by the PTLXAU when the originating telex subscriber requests deferred delivery of his message. The procedures for requesting deferred delivery are defined in Recommendation U.204.
+
+*Note* – The code expressions to be used for the selection of the elements of service described in §§ 4.3.8 and 4.3.9 by the telex subscriber, are shown in Table 4/F.421.
+
+TABLE 4/F.421
+
+##### **Code expressions for the use of IPM elements of service**
+
+| IPM element of service         | Format                |
+|--------------------------------|-----------------------|
+| Disclosure of other recipients | DUR                   |
+| Deferred delivery              | DEF → <value>         |
+| Delivery notification          | BT, ACK <sup>a)</sup> |
+
+<sup>a)</sup> The request for delivery notification may be given together with the code for end of adresse (es) (BT) if delivery notification is required.
+
+*Note* – The symbol → equals a space.
+
+#### 4.3.10 *Other elements of service*
+
+Elements of service of the basic IPM service other than those specified above shall be set by the PTLXAU in accordance with the requirements of the domain to which it belongs.
+
+## ANNEX A (to Recommendation F.421)
+
+### **Abbreviations**
+
+|        |                                                     |
+|--------|-----------------------------------------------------|
+| A/B    | Answerback                                          |
+| ACK    | Request for Delivery Notification Signal            |
+| ADM    | Administration Management Domain                    |
+| BT     | End of Address(es) Signal                           |
+| CI     | Conversation Impossible                             |
+| COM    | Common Name                                         |
+| CTN    | Country Name                                        |
+| DDT    | Domain Defined Attribute Type                       |
+| DDV    | Domain Defined Attribute Value                      |
+| DEF    | Deferred Delivery                                   |
+| DUR    | Disclosure of other Recipients                      |
+| EOA    | End of Address                                      |
+| EOM    | End of Message                                      |
+| EOT    | End of Transaction                                  |
+| FAX    | Facsimile                                           |
+| GEN    | Generation Qualifier                                |
+| GIV    | Given Name                                          |
+| I      | Initials                                            |
+| IP     | Interpersonal                                       |
+| IPM    | Interpersonal Messaging                             |
+| MT     | Message Transfer                                    |
+| MTS    | Message Transfer System                             |
+| NP     | The called party is not, or no longer, a subscriber |
+| NUS    | Numeric User Identifier                             |
+| O/R    | Originator/Recipient                                |
+| ORG    | Organization Name                                   |
+| OUN    | Organization Unit Name(s)                           |
+| P2     | IPM Protocol                                        |
+| PRI    | Private Domain Name                                 |
+| PTLXAU | Public Telex Access Unit                            |
+| SUR    | Surname                                             |
+| TID    | Terminal Identifier                                 |
+| TLX    | Telex                                               |
+| TTX    | Teletex                                             |
+| UTC    | Universal Coordinated Time                          |
+| VTX    | Videotex                                            |
+| WRU    | Who Are You                                         |
+| +      | End of Single O/R Address signal                    |
+| →      | Space                                               |
+
+*Note 1* – For a glossary of terms see Annex A to Recommendation F.400.
+
+*Note 2* – For references see Recommendation F.400.
+
+## ANNEX B (to Recommendation F.421)
+
+### **Actions to be taken by the PTLXAU/examples**
+
+Basic IPM elements of service and essential optional IPM user facilities which have to be processed by the PTLXAU in the case where a message is sent from the IPM service to the telex service direction (Table B-1/F.421).
+
+TABLE B-1/F.421
+
+| Reference<br>Rec. F.400<br>Annex B | Elements of service             | Action to be taken                                                                      | Examples                          |
+|------------------------------------|---------------------------------|-----------------------------------------------------------------------------------------|-----------------------------------|
+| B.5                                | Authorizing users indication    | Display in message heading                                                              | Authority : → <value>             |
+| B.6                                | Auto-forwarded indication       | Ignore                                                                                  |                                   |
+| B.8                                | Blind copy recipient indication | Display the O/R descriptor information of the blind copy recipient(s)                   | BCC → <value>                     |
+| B.9                                | Body part encryption indication | The PTLXAU shall send a non-delivery notification to the originator                     |                                   |
+| B.12                               | Content type indication         | National matter for content types different than P2                                     |                                   |
+| B.13                               | Conversion prohibition          | If ITA2, ignore. Otherwise the PTLXAU generates a non-delivery notification             |                                   |
+| B.15                               | Converted indication            | Ignore                                                                                  |                                   |
+| B.18                               | Cross referencing indication    | Display in message heading                                                              | Reference → <value>               |
+| B.21                               | Delivery notification           | The PTLXAU shall send a delivery notification to the originator                         |                                   |
+| B.22                               | Delivery time stamp indication  | Ignore                                                                                  |                                   |
+| B.25                               | Disclosure of other recipients  | Disclose all recipients                                                                 |                                   |
+| B.26                               | DL expansion history indication | Ignore                                                                                  |                                   |
+| B.29                               | Expiry date indication          | Display in message heading                                                              | Message invalid after : → <value> |
+| B.31                               | Forwarded IP-message indication | the PTLXAU shall build a message heading for each IP-message contained in the body part |                                   |
+| B.32                               | Grade of delivery selection     | National matter                                                                         |                                   |
+| B.34                               | Implicit conversion             | Convert to telex according to Rec. X.408                                                |                                   |
+| B.35                               | Importance indication           | Display in message heading                                                              | Message importance: → <value>     |
+| B.37                               | IP-message identification       | display in message heading                                                              | Message reference: → <value>      |
+| B.38                               | Language indication             | Ignore                                                                                  |                                   |
+| B.39                               | Latest delivery designation     | National matter                                                                         |                                   |
+
+TABLE B-1/F.421 (cont.)
+
+| References<br>Rec. F.400<br>Annex B | Elements of message                           | Action to be taken                                                                                                      | Examples                                                         |
+|-------------------------------------|-----------------------------------------------|-------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------|
+| B.41                                | Message identification                        | Ignore                                                                                                                  |                                                                  |
+| B.45                                | Multi-destination delivery                    | Deliver the message to all recipients                                                                                   |                                                                  |
+| B.46                                | Multi-part body                               | Messages containing not supported body parts are not delivered. Send back a non-delivery notification to the originator |                                                                  |
+| B.47                                | Non-delivery notification                     | The PTLXAU shall generate a delivery report                                                                             |                                                                  |
+| B.48                                | Non-receipt notification request              | Ignore                                                                                                                  |                                                                  |
+| B.52                                | Obsoleting indication                         |                                                                                                                         | Obsoletes: → <value>                                             |
+| B.54                                | Original encoded information types indication | Ignore                                                                                                                  |                                                                  |
+| B.55                                | Originator indication                         | Ignore                                                                                                                  |                                                                  |
+| B.56                                | Originator request alternate recipient        | National matter                                                                                                         |                                                                  |
+| B.62                                | Primary and copy recipients indication        | Display the O/R descriptor information of the recipient(s) in the message heading                                       | TO: → <value><br>TO: → <value><br>CC: → <value><br>CC: → <value> |
+| B.63                                | Probe                                         | National matter                                                                                                         |                                                                  |
+| B.67                                | Receipt notification request indication       | Ignore                                                                                                                  |                                                                  |
+| B.72                                | Reply request indication                      | Display in message heading                                                                                              | Reply → requested →<br>by → sender                               |
+| B.73                                | Replying IP – message indication              | Display in message heading                                                                                              | Reply to message: →<br><value>                                   |
+| B.80                                | Sensibility indication                        | Display in message heading just above text of body                                                                      |                                                                  |
+| B.88                                | Subject indication                            | Display in message heading just above text of body                                                                      | Subject: → <value>                                               |
+| B.89                                | Submission time stamp                         | Display in message heading                                                                                              | Submitted: → <value><br>→ UTC                                    |
+| B.90                                | Typed body                                    | Ignore                                                                                                                  |                                                                  |
+
+Note – The symbol → equals a space.
+
+## ANNEX C
+
+(to Recommendation F.421)
+
+### IPM message to telex
+
+General layout of a message originated by an IPM service user and delivered by the PTLXAU to a telex subscriber.
+
+![Diagram showing the general layout of an IPM message to a telex subscriber. A vertical double-headed arrow on the left is labeled 'Telex call'. On the right, a box labeled 'IP message' contains several nested boxes. From top to bottom, these are: 'Exchange of answerbacks between telex subscriber and PTLXAU', 'For recall "text and O/R addresses"', 'PTLXAU identifier', 'Message heading', 'Body', and another 'Exchange of answerbacks'.](cab0834804fb031b43865554cc8d06ab_img.jpg)
+
+Diagram illustrating the general layout of an IPM message to a telex subscriber. The diagram shows a vertical stack of components within an "IP message" box, corresponding to a "Telex call".
+
+- A vertical double-headed arrow on the left is labeled **Telex call**.
+- The main content area on the right is labeled **IP message** and consists of the following sequence:
+  - Exchange of answerbacks between telex subscriber and PTLXAU
+  - Box: For recall “text and O/R addresses”
+  - Box: PTLXAU identifier
+  - Large Box containing:
+    - Box: Message heading
+    - Box: Body
+  - Exchange of answerbacks between telex subscriber and PTLXAU
+
+CCITT – 0100750-89
+
+Diagram showing the general layout of an IPM message to a telex subscriber. A vertical double-headed arrow on the left is labeled 'Telex call'. On the right, a box labeled 'IP message' contains several nested boxes. From top to bottom, these are: 'Exchange of answerbacks between telex subscriber and PTLXAU', 'For recall "text and O/R addresses"', 'PTLXAU identifier', 'Message heading', 'Body', and another 'Exchange of answerbacks'.
+
+Display of the originator O/R address related information to the telex user in the message heading:
+
+a) Two-stage selection:
+
+FROM:→ GIV→francois  
+SUR→maurer  
+ORG→swiss→ptt  
+ADM→arcom400  
+CTN→ch
+
+b) One-stage selection:
+
+FROM:→(F.74 A/B)
+
+## ANNEX D
+
+(to Recommendation F.421)
+
+### **Telex message to IPM**
+
+(Two-stage selection)
+
+General layout of a message originated by a telex subscriber using the two-stage selection, submitted to the PTLXAU for delivery to the IPM service.
+
+![Sequence diagram of a telex call showing message structure and exchange of answerbacks.](a26e142d3df5bef41a84a9dd099d7825_img.jpg)
+
+```
+
+        graph TD
+        A[Exchange of answerbacks between telex subscriber and PTLXAU] --> B[Input of service identifier and O/R address(es) according to Table 1/F.421]
+        subgraph "First message"
+        B --> C[Code expressions "DUR", "DEF" or "ACK" (only if elements of service B19, B.21 or B.25 are requested)]
+        C --> D[Text of the message]
+        D --> E[EOM signal]
+        end
+        subgraph "Follow-up message(s)"
+        E --> F[Input of service identifier and O/R address(es) according to Table 1/F.421]
+        F --> G[Code expressions "DUR", "DEF" or "ACK" (only if elements of service B19, B.21 or B.25 are requested)]
+        G --> H[Text of the message]
+        H --> I[EOM signal]
+        I --> J[EOT signal]
+        end
+        J --> K[Exchange of answerbacks between telex subscriber and PTLXAU]
+    
+```
+
+CCITT - 0100760-89
+
+Sequence diagram of a telex call showing message structure and exchange of answerbacks.

marked/F/T-REC-F.600-200404-I_PDF-E/raw.md

@@ -0,0 +1,486 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+# **ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# **F.600**
+
+(04/2004)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Data transmission services
+
+---
+
+**Service and operational principles for public  
+data transmission service**
+
+ITU-T Recommendation F.600
+
+---
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multidestination satellite services         | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | <b>F.600–F.699</b> |
+| <b>AUDIOVISUAL SERVICES</b>                                     | F.700–F.799        |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>HUMAN FACTORS</b>                                            | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **ITU-T Recommendation F.600**
+
+# **Service and operational principles for public data transmission service**
+
+## **Summary**
+
+This Recommendation contains the general service and operational principles to be followed for the international public data transmission service. The general model of international public data transmission service is outlined. This Recommendation includes important aspects of data transmission service – addressing, quality of service, call progress signals, multicast operation, user classes of service and optional user facilities. The general provisions between Administrations and the general provisions between the Administration and the customer are also described.
+
+The overview of the interrelationship between the relevant Recommendations necessary for offering data transmission service is in the scope of this Recommendation.
+
+###### **Source**
+
+ITU-T Recommendation F.600 was approved on 29 April 2004 by ITU-T Study Group 17 (2001-2004) under the ITU-T Recommendation A.8 procedure.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure *e.g.* interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 2004
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## CONTENTS
+
+|                                                                             | Page |
+|-----------------------------------------------------------------------------|------|
+| 1 Scope                                                                     | 1    |
+| 2 References                                                                | 2    |
+| 3 Terminology                                                               | 4    |
+| 4 Abbreviations                                                             | 4    |
+| 5 General model of international PDTS                                       | 4    |
+| 6 Addressing aspects                                                        | 5    |
+| 7 Quality of service                                                        | 6    |
+| 8 Call progress signals                                                     | 6    |
+| 9 Multicast operation                                                       | 6    |
+| 10 User classes of service, categories of access                            | 6    |
+| 11 Optional user facilities                                                 | 7    |
+| 12 Data compression and security                                            | 7    |
+| 13 Administrative arrangements for international Closed User Groups         | 7    |
+| 14 Administrative arrangements for international Permanent Virtual Circuits | 7    |
+| 15 Charging principles                                                      | 7    |
+| 16 Duration of service                                                      | 8    |
+| 17 Outages                                                                  | 8    |
+| 18 Service calls                                                            | 8    |
+| 19 General provisions between Administrations                               | 8    |
+| 20 General provisions between Administration and customer                   | 8    |
+
+
+
+# Service and operational principles for public data transmission service
+
+## **1 Scope**
+
+**1.1** The establishment in various countries of public data networks creates the need to produce Recommendations to facilitate the provision of international public data transmission services. This Recommendation lays down the general service and operational principles to be followed for international data transmission services.
+
+This Recommendation provides an overview of interrelationship between the relevant Recommendations necessary for establishing, maintaining and offering the public data transmission service.
+
+**1.2** Public Data Transmission Service (PDTS) is a service established by an Administration and provides exchange of data between service users.
+
+NOTE – In this Recommendation, the expression "Administration" is used to indicate both a telecommunication administration and a Recognized Operating Agency (ROA). An international PDTS may be provided through the interworking of national Public Data Networks (PDNs) and Integrated Services Digital Networks (ISDNs). Public data networks are established and operated by the Administration for the specific purpose of providing data transmission service.
+
+**1.3** Public data networks and public data transmission services do not include the Data Terminal Equipment (DTE). Therefore, additional capabilities arise because DTEs do not belong to PDNs and PDTSs. PDTS is assumed to be equivalent to the bearer service (see the definition of bearer service in ITU-T Recs I.112 and I.230). Public Data Networks in Open Systems Interconnection (OSI) environments typically provide three lower layers: physical layer, data link layer and network layer (see ITU-T Recs X.200 | ISO/IEC 7498-1 and X.300).
+
+Various services based on PDTS may be operated by Administrations. Those services are assumed to be equivalent to teleservices (refer to ITU-T Recs I.112 and I.240 for the definition of teleservice). See Figure 1.
+
+**1.4** Four types of data transmission services are identified: circuit switched, packet switched, frame relay and leased circuit PDTS. Those services are based on Circuit-Switched Public Data Networks (CSPDNs), Packet-Switched Public Data Networks (PSPDNs), Frame Relay Public Data Networks (FRPDNs) and Leased Circuits.
+
+**1.5** This Recommendation does not cover international leased circuit PDNs. Also, this Recommendation does not cover public data transmission services offered by Integrated Services Digital Networks (ISDNs). Access to PDTS in one country through the Public Switched Telephone Network (PSTN) in another country is also out of the scope of this Recommendation. This Recommendation does not cover data transmission possibilities provided by IP-based networks or data transmission possibilities provided by modems on Public Switched Telephone Network (PSTN).
+
+![Diagram illustrating the environment for data transmission service. It shows two Data Terminal Equipment (DTE) units connected to a central Data network via User/network interfaces. Each interface connects to a Data Circuit-Terminating Equipment (DCE) which is part of the Data network. The Data network provides a Data transmission service (bearer service) between the two User/network interfaces. Teleservices (facsimile service, computer service, etc.) are shown as being provided by the Data network to the DTEs. The diagram is labeled F.600_F01.](3121ebddccf183ca63bb9781be440a7e_img.jpg)
+
+```
+
+graph LR
+    subgraph DTE_Left [DTE]
+        L_DTE[ ]
+    end
+    subgraph Network [Data network]
+        L_DCE[DCE] --- R_DCE[DCE]
+    end
+    subgraph DTE_Right [DTE]
+        R_DTE[ ]
+    end
+    L_DTE --- L_IF(( ))
+    L_IF --- L_DCE
+    R_DCE --- R_IF(( ))
+    R_IF --- R_DTE
+    
+    L_IF -.->|User/network interface| L_IF
+    R_IF -.->|User/network interface| R_IF
+    
+    L_IF <==>|Data transmission service  
+(bearer service)| R_IF
+    L_DTE <==>|Teleservices  
+facsimile service, computer service, etc.| R_DTE
+
+```
+
+Diagram illustrating the environment for data transmission service. It shows two Data Terminal Equipment (DTE) units connected to a central Data network via User/network interfaces. Each interface connects to a Data Circuit-Terminating Equipment (DCE) which is part of the Data network. The Data network provides a Data transmission service (bearer service) between the two User/network interfaces. Teleservices (facsimile service, computer service, etc.) are shown as being provided by the Data network to the DTEs. The diagram is labeled F.600\_F01.
+
+DTE Data terminal equipment (subscriber's terminal, teleservice server, etc.)  
+DCE Data circuit-terminating equipment
+
+**Figure 1/F.600 – The environment for data transmission service**
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- ITU-T Recommendation E.116 (1997), *International telecommunication charge card service*.
+- ITU-T Recommendation E.164 (1997), *The international public telecommunication numbering plan*.
+- ITU-T Recommendation F.17 (1992), *Operational aspects of service telecommunications*.
+- ITU-T Recommendation I.112 (1993), *Vocabulary of terms for ISDNs*.
+- ITU-T Recommendation I.230 (1988), *Definition of bearer service categories*.
+- ITU-T Recommendation I.240 (1988), *Definition of teleservices*.
+- ITU-T Recommendation X.1 (2000), *International user classes of service in, and categories of access to, public data networks and Integrated Services Digital Networks (ISDNs)*.
+- ITU-T Recommendation X.2 (2000), *International data transmission services and optional user facilities in public data networks and ISDNs*.
+- ITU-T Recommendation X.6 (1997), *Multicast service definition*, plus Amendment 1 (2000), *Frame relay PVC multicast service definition*.
+- ITU-T Recommendation X.7 (2004), *Technical characteristics of data transmission services*.
+- ITU-T Recommendation X.92 (1988), *Hypothetical reference connections for public synchronous data networks*.
+- ITU-T Recommendation X.96 (2000), *Call progress signals in public data networks*.
+
+- ITU-T Recommendation X.110 (2002), *International routing principles and routing plan for Public Data Networks.*
+- ITU-T Recommendation X.111 (2003), *Principles for the routing of international frame relay traffic.*
+- ITU-T Recommendation X.115 (1995), *Definition of address translation capability in public data networks.*
+- ITU-T Recommendation X.116 (1996), *Address translation registration and resolution protocol.*
+- ITU-T Recommendation X.121 (2000), *International numbering plan for public data networks.*
+- ITU-T Recommendation X.130 (1988), *Call processing delays in public data networks when providing international synchronous circuit-switched data services.*
+- ITU-T Recommendation X.131 (1988), *Call blocking in public data networks when providing international synchronous circuit-switched data services.*
+- ITU-T Recommendation X.135 (1997), *Speed of service (delay and throughput) performance values for public data networks when providing international packet-switched services.*
+- ITU-T Recommendation X.136 (1997), *Accuracy and dependability performance values for public data networks when providing international packet-switched services.*
+- ITU-T Recommendation X.137 (1997), *Availability performance values for public data networks when providing international packet-switched services.*
+- ITU-T Recommendation X.144 (2003), *User information transfer performance parameters for public frame relay data networks.*
+- ITU-T Recommendation X.145 (2003), *Connection establishment and disengagement performance parameters for public Frame Relay data networks providing SVC services.*
+- ITU-T Recommendation X.146 (2000), *Performance objectives and quality of service classes applicable to frame relay.*
+- ITU-T Recommendation X.147 (2003), *Frame Relay network availability.*
+- ITU-T Recommendation X.180 (1988), *Administrative arrangements for international Closed User Groups (CUGs).*
+- ITU-T Recommendation X.181 (1988), *Administrative arrangements for the provision of international permanent virtual circuits (PVCs).*
+- ITU-T Recommendation X.200 (1994) | ISO/IEC 7498-1:1994, *Information technology – Open Systems Interconnection – Basic reference model: The basic model.*
+- ITU-T Recommendation X.272 (2000), *Data compression and privacy over frame relay networks.*
+- ITU-T Recommendation X.300 (1996), *General principles for interworking between public networks and between public networks and other networks for the provision of data transmission services.*
+- ITU-T Recommendation X.371/Y.1402 (2001), *General arrangements for interworking between Public Data Networks and the Internet.*
+
+## 3 Terminology
+
+The definitions of terms used in this Recommendation are in ITU-T Rec. X.7.
+
+NOTE – Within this Recommendation the term "Frame Relay Public Data Network (FRPDN)" is used. Some other Recommendations use the term "Public Frame Relay Data Network (PFRDN)". Both terms have absolutely the same meaning.
+
+## 4 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|       |                                       |
+|-------|---------------------------------------|
+| CSPDN | Circuit-Switched Public Data Network  |
+| CUG   | Closed User Group                     |
+| DCE   | Data Circuit-terminating Equipment    |
+| DTE   | Data Terminal Equipment               |
+| FRPDN | Frame Relay Public Data Network       |
+| IDSE  | International Data Switching Exchange |
+| ISDN  | Integrated Services Digital Network   |
+| OSI   | Open Systems Interconnection          |
+| PSPDN | Packet-Switched Public Data Network   |
+| PDN   | Public Data Network                   |
+| PDTS  | Public Data Transmission Service      |
+| PSTN  | Public Switched Telephone Network     |
+| PVC   | Permanent Virtual Circuit             |
+| ROA   | Recognized Operating Agency           |
+
+## 5 General model of international PDTS
+
+**5.1** An international PDTS is based on an interconnection of national PDTSs. Such an interconnection is achieved with the interconnection of International Data Switching Exchanges (IDSEs) in relevant countries. The route for a call consists of three parts (see Figure 2):
+
+- an originating national network part, from calling DTE to originating IDSE through the originating national PDN;
+- an international network part, from the originating IDSE to the destination IDSE;
+- a destination national network part, from the destination IDSE to the called DTE through the destination national PDN.
+
+![Diagram illustrating the components of an international call. The diagram shows a sequence of components from left to right: Calling DTE, Original national network part (containing a National network and an IDSE), International network part (containing an International link), Destination national network part (containing an IDSE and a National network), and Called DTE. A double-headed arrow at the bottom indicates 'The route for an international call'. A legend at the bottom left defines DTE as Data terminal equipment and IDSE as International data switching exchange. The label F.600_F02 is in the bottom right corner.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+```
+
+graph LR
+    A[Calling DTE] --- B[Original national network part]
+    subgraph B [Original national network part]
+        B1[National network] --- B2[IDSE]
+    end
+    B2 --- C[International link]
+    subgraph C [International network part]
+        C1[International link]
+    end
+    C1 --- D[Destination national network part]
+    subgraph D [Destination national network part]
+        D1[IDSE] --- D2[National network]
+    end
+    D2 --- E[Called DTE]
+
+```
+
+The diagram illustrates the components of an international call. It shows a sequence of components from left to right: Calling DTE, Original national network part (containing a National network and an IDSE), International network part (containing an International link), Destination national network part (containing an IDSE and a National network), and Called DTE. A double-headed arrow at the bottom indicates 'The route for an international call'. A legend at the bottom left defines DTE as Data terminal equipment and IDSE as International data switching exchange. The label F.600\_F02 is in the bottom right corner.
+
+Diagram illustrating the components of an international call. The diagram shows a sequence of components from left to right: Calling DTE, Original national network part (containing a National network and an IDSE), International network part (containing an International link), Destination national network part (containing an IDSE and a National network), and Called DTE. A double-headed arrow at the bottom indicates 'The route for an international call'. A legend at the bottom left defines DTE as Data terminal equipment and IDSE as International data switching exchange. The label F.600\_F02 is in the bottom right corner.
+
+**Figure 2/F.600 – Components of an international call**
+
+**5.2** Various types of PDNs (and/or other networks) may interwork within a national network part. The originating national network part and the destination national network part may be different types of PDNs (or other networks). The international network part may consist of interworked IDSEs belonging to different networks of various countries. See ITU-T Recs X.1 and X.7 for possible interworking between networks providing data transmission. See ITU-T Rec. X.371/Y.1402 for interworking between PDNs and the Internet.
+
+**5.3** The planning of originating and destination PDNs is a national matter. Planning of originating and destination traffic routes is also a national matter. However, the quality of service of an international PDTs has to be taken into account when planning national PDNs, originating and destination traffic routes.
+
+The planning of international traffic routes is the responsibility of the concerned Administrations and is subject to bilateral agreement.
+
+**5.4** Interworked national PDNs may be interconnected directly or via intermediate countries. For PSPDNs, FRPDNs and CSPDNs, routing principles of international data traffic are outlined in ITU-T Recs X.110 and X.111.
+
+**5.5** Administrations should compile information concerning service parameters of their networks for dissemination upon the request of the interested Administrations to enable the selection of the PDN for interworking and the planning of such interworking.
+
+**5.6** The total connection should comply with ITU-T Rec. X.92 for PSPDN and CSPDN. Hypothetical Reference Connections for FRPDNs are for further study.
+
+**5.7** Access to a national PDTs may be either *direct access* (without any intermediate switched network) or *port access* (via an intermediate switched network). Planning of access is a national matter. Access to a destination national PDTs via a PSTN or an ISDN of an originating country should be referred to as port access.
+
+**5.8** General aspects of PDTs including technical characteristics of PDTs in PDNs are outlined in ITU-T Rec. X.7.
+
+## **6 Addressing aspects**
+
+**6.1** Numbering in PDNs should comply with the International Numbering Plan specified in ITU-T Rec. X.121. PDNs may identify some DTEs by numbers from the E.164 numbering plan. FRPDNs may use either the X.121 or E.164 numbering plans.
+
+**6.2** Customers of PSPDNs and FRPDNs may use (where provided) alternative addressing, which does not correspond to the requirements of ITU-T Recs X.121 and E.164, for example some kinds of user-friendly addresses such as mnemonic addresses. In this case, PSPDN and FRPDN should have an address translation service which enables the PDNs to route calls to the proper X.121/E.164 address when the called address is out of the scope of X.121/E.164 addressing. Usage of the address translation service within the national PDNs is a national matter. Offering address translation capability in an international PDTS requires special provisions agreed between the Administrations concerned.
+
+**6.3** The definition of the address translation capability is outlined in ITU-T Recs X.115 and X.116.
+
+## **7 Quality of service**
+
+**7.1** Quality of service of an international PDTS is a subject of common responsibility of the Administrations concerned. Quality of service of a national network part is the responsibility of each relevant Administration. Quality of service of an international network part is the responsibility of the concerned (including transit) Administrations.
+
+**7.2** Apportioning of quality of service parameter values (national and international portions) should comply with ITU-T Recs X.135, X.136 and X.137 for PSPDN; ITU-T Recs X.130, X.131 for CSPDN; ITU-T Recs X.144, X.145, X.146 and X.147 for FRPDN.
+
+**7.3** Apportioning of quality of service parameter values of international network part is subject to agreement between all Administrations involved in the provision of international network part.
+
+## **8 Call progress signals**
+
+**8.1** Call progress signals inform the caller about the progress of the call including the circumstances which may have prevented the connection.
+
+**8.2** Call progress signals for CSPDN, PSPDN and FRPDN are defined in ITU-T Rec. X.96.
+
+## **9 Multicast operation**
+
+**9.1** Multicast service facilitates the provision of point-to-multipoint (multicast) data service. Using a multicast service, the customer (sender) must first establish a connection to the entity called multicast server, and after that data units are transferred by multicast server to other participants of the multicast service (receivers).
+
+**9.2** Establishment of national multicast services and methods of establishing multicast services (inside or outside the national PDN), etc., are a national matter. Establishment of international multicast services (establishing of international multicast groups, principles of interworking of national multicast servers) is subject to agreement between concerned Administrations.
+
+**9.3** Multicast services in PSPDN and FRPDN are defined in ITU-T Rec. X.6.
+
+## **10 User classes of service, categories of access**
+
+**10.1** PDTSs offer to users so-called "basic user facilities". Basic user facilities are defined by user classes of service and categories of access.
+
+**10.2** User class of service is a category of PDTS in which the DTE operation mode, data signalling rate, call control signalling rates and code structure (in start-stop mode) are standardized.
+
+**10.3** User classes of service within the national PDTS is a national matter; user classes of service provided internationally are subject to agreement between the concerned Administrations. Nationally and internationally provided user classes of service may not coincide.
+
+**10.4** Category of access identifies the method by which the DTE gains access to a specific data transmission service. Direct or port access may be used. Usage of category of access is a national matter.
+
+**10.5** User classes of service and categories of access are outlined in ITU-T Rec. X.1.
+
+## **11 Optional user facilities**
+
+**11.1** Optional user facilities modify or complement basic user facilities. An optional user facility cannot be offered to a user as a stand-alone facility; it may be offered only in association with a basic user facility.
+
+**11.2** Optional user facilities for international PDTS are outlined in ITU-T Rec. X.2.
+
+**11.3** Concerned Administrations should procure internationally all the essential user facilities (see ITU-T Rec. X.2). Additional optional user facilities may or may not be provided.
+
+## **12 Data compression and security**
+
+Techniques for data compression and security may be provided in FRPDNs according to ITU-T Rec. X.272.
+
+## **13 Administrative arrangements for international Closed User Groups**
+
+**13.1** Closed User Group (CUG) facilities (example of an optional user facility) enable users for access to/from users having one or more of these facilities. The basic facility enables customers to belong to one or more CUGs and to make/receive calls only to/from other customers in the same CUG.
+
+**13.2** Concerned Administrations should observe the following when managing CUGs:
+
+- For each international CUG, a "responsible subscriber" has to be nominated. Such a nomination is subject to agreement between all participants of the CUG.
+- The Administration of the country hosting the "responsible subscriber" (coordinating Administration) shall act as a controlling and coordinating Administration for that CUG and shall carry out discussions with the responsible subscriber about changes to the CUG. The coordinating Administration shall also be responsible for the allocation of international CUG numbers.
+
+**13.3** Administrative arrangements for international CUGs are defined in ITU-T Rec. X.180.
+
+## **14 Administrative arrangements for international Permanent Virtual Circuits**
+
+**14.1** The international application of the Permanent Virtual Circuit (PVC) service is subject to agreement between the concerned Administrations. Subscribers to be connected to an international PVC shall nominate a "responsible subscriber". That subscriber is responsible for all organizational matters relating to the international PVC.
+
+**14.2** The Administration of the country hosting the responsible subscriber (source Administration) shall act as a controlling and coordinating Administration for that international PVC and shall carry out the discussions with the responsible subscriber about any changes to the international PVC.
+
+**14.3** Provisions of the international PVC are defined in ITU-T Rec. X.181.
+
+## **15 Charging principles**
+
+Charging principles for PDNs are defined in ITU-T D-series Recommendations.
+
+## **16 Duration of service**
+
+International PDTSS are, in principle, continuously available. Duration of the service should not be limited, unless this contravenes national law.
+
+## **17 Outages**
+
+**17.1** Administrations may temporarily withdraw the whole or part of the service from operation for the purpose of maintenance and enhancements necessary to ensure that the service is kept in a proper working condition.
+
+**17.2** Administrations shall endeavour to minimize the impact of such service withdrawals. It is the responsibility of an Administration planning to withdraw a service to notify other concerned Administrations. Aspects relating to network availability and service outages for PSPDNs and FRPDNs are covered in ITU-T Recs X.137 and X.147 respectively.
+
+## **18 Service calls**
+
+**18.1** Service telecommunications should be established among the interested Administrations to facilitate the exchange of information necessary to administer and maintain services, network management, accounting, handling of customer complaints, etc.
+
+**18.2** Administrations are encouraged to make service telecommunications free of charge.
+
+**18.3** Aspects of service telecommunications are laid down in ITU-T Rec. F.17.
+
+## **19 General provisions between Administrations**
+
+**19.1** The international PDTSS should be operated in the automatic mode.
+
+**19.2** Administrations should reach mutual agreement on the information needed to be exchanged to sustain the international PDTSS and facilities offered. Administrations are not obliged to offer internationally all facilities available nationally.
+
+**19.3** Administrations should reach mutual agreement on the upgrading, enhancement and expansion of the service. Each Administration should supply the concerned Administrations with a number of copies of its subscriber directories (see below).
+
+## **20 General provisions between Administration and customer**
+
+**20.1** The Administration should inform the customers about the data transmission services available internationally. This should include information on:
+
+- service offered, including user classes of service, categories of access, optional user facilities;
+- charges;
+- quality of service expected, including priority and service classes;
+- call progress signals, error messages, diagnostic codes and their meaning;
+- fault reporting procedures;
+- procedures for resolving disputes including billing disputes;
+- directory facilities;
+- other information relating to service problems.
+
+**20.2** Customers may select user classes of service, categories of access, optional user facilities, priority and service classes.
+
+**20.3** Administrations must assist customers with the changing capabilities of the services offered. Customer Help Facility should be established. The exact organization of Customer Help Facility is a national matter, but at least the following customer assistance should be offered:
+
+- availability of services;
+- information and notification on planned outages;
+- directory service.
+
+**20.4** The International Telecommunication Charge Card Service allows the holder of a telecommunication charge card to make use of a variety of services provided by the card acceptor (i.e., the public data network from which services are being obtained) and to have the charges billed to the customer's account by the card issuer. The scope of public data transmission services for which the card applies will be subject to agreements between the card issuer and card acceptor.
+
+This Recommendation specifically entails the use of a telecommunication charge card issued by an ROA in compliance with ITU-T Rec. E.116.
+
+The use of the International Telecommunication Charge Card Service in a public data network depends on agreements between the card acceptors and card issuers. Major items to be covered may include:
+
+- types of service for which cards may be used;
+- basis for settlement of service charges and surcharges;
+- prevention of fraudulent use of cards;
+- procedures for uncollectible and unbillable services.
+
+**20.5** Directory services available to the customers should be in accordance with national laws and regulations regarding the suitability of publication of the information and the form in which it is published. Directories may be issued in form of printed materials. Electronic directories are also recommended.
+
+**20.6** Printed directories for international use should be updated at least once a year. Customers may decide to be excluded from the directory. The page size should not be larger than an A4 format. The directory for international use should be set in roman letters. The number published shall be the one that the calling customer must transmit to obtain the called customer. The directory normally has to be written in a language used in the country; use of explanatory notes in whatever official ITU language is recommended.
+
+**20.7** Electronic directories should be accessed from a DTE of the data network providing the PDTS. Access from other DTEs is also encouraged. Principles of electronic directories for PDTSs (e.g., according ITU-T X.500-series Recommendations) are for further study.
+
+
+
+
+
+# SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                              |
+| Series B        | Means of expression: definitions, symbols, classification                                                                      |
+| Series C        | General telecommunication statistics                                                                                           |
+| Series D        | General tariff principles                                                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                              |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                |
+| Series G        | Transmission systems and media, digital systems and networks                                                                   |
+| Series H        | Audiovisual and multimedia systems                                                                                             |
+| Series I        | Integrated services digital network                                                                                            |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                    |
+| Series K        | Protection against interference                                                                                                |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant                                        |
+| Series M        | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                |
+| Series O        | Specifications of measuring equipment                                                                                          |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                   |
+| Series Q        | Switching and signalling                                                                                                       |
+| Series R        | Telegraph transmission                                                                                                         |
+| Series S        | Telegraph services terminal equipment                                                                                          |
+| Series T        | Terminals for telematic services                                                                                               |
+| Series U        | Telegraph switching                                                                                                            |
+| Series V        | Data communication over the telephone network                                                                                  |
+| Series X        | Data networks and open system communications                                                                                   |
+| Series Y        | Global information infrastructure, Internet protocol aspects and Next Generation Networks                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                           |
+
+![Barcode with the number * 2 5 8 5 3 *](97fe9069356cc2a84e8e70673e405958_img.jpg)
+
+A barcode consisting of vertical black lines of varying widths. Below the barcode, the text "\* 2 5 8 5 3 \*" is printed.
+
+Barcode with the number \* 2 5 8 5 3 \*

marked/F/T-REC-F.64-198811-I_PDF-E/raw.md

@@ -0,0 +1,297 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.64**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# **OPERATIONS AND QUALITY OF SERVICE TELEGRAPH SERVICES** ---
+
+## **DETERMINATION OF THE NUMBER OF INTERNATIONAL TELEX CIRCUITS REQUIRED TO CARRY A GIVEN VOLUME OF TRAFFIC**
+
+**ITU-T Recommendation F.64**
+
+(Extract from the *Blue Book*)
+
+---
+
+### NOTES
+
+1 ITU-T Recommendation F.64 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+### Recommendation F.64
+
+## DETERMINATION OF THE NUMBER OF INTERNATIONAL TELEX CIRCUITS REQUIRED TO CARRY A GIVEN VOLUME OF TRAFFIC
+
+The CCITT,
+
+*considering*
+
+(a) that it is essential to provide an adequate number of circuits between two telex networks in order to provide the rapid service stipulated in Recommendation F.60;
+
+(b) that the use of tables for the determination of the number of circuits as a function of the traffic to be dealt with during the busy hour is an established practice in all Administrations, and is a convenient means of indicating a standard;
+
+(c) that international telex circuits may be selected either at manual positions, or via automatic switching equipment, particularly where subscriber-to-subscriber selection is employed between two networks;
+
+*unanimously declares*
+
+(1) that Administrations should use Tables 1/F.64 or 2/F.64 below, according to the system of selection employed (i.e. manual selection or automatic selection) in the international service;
+
+(2) Administrations should aim for full availability of circuits on intercontinental and ARQ radio routes operated with signalling in accordance with Recommendations U.1, U.11, U.12 and U.20. Where an Administration is unable to provide the full availability, it should provide an availability to achieve not less than 90% of the full availability capacity relative to the number of circuits on the route at a grade of service of one in 50.
+
+### 1 Introduction
+
+1.1 Table 1/F.64 shows values for manual traffic carried. If for the purpose of design (as distinct from the maintenance of rapid service) it is desired to obtain values for offered traffic in erlangs, these may be determined by adding the respective values of lost traffic to the figures for carried traffic in Table 1/F.64.
+
+1.2 Table 1/F.64 is directly applicable only to full-availability groups of circuits that are operated either wholly as bothway circuits, or wholly as unidirectional circuits.
+
+1.3 Tables 2/F.64 shows values for traffic offered in the automatic service and is directly applicable to full-availability groups and groups with availabilities between 10 and 50.
+
+Given the traffic offered (A) in erlangs and the availability (K), the number of circuits required to provide a loss probability (B) of 0.02 may be determined from Table 2/F.64. Groups of up to 200 circuits and availabilities of 10, 20, 30, 50 and N circuits (N circuits corresponding to full availability) are covered. The method of applying the table is shown in Figure 1/F.64.
+
+1.4 Where groups of circuits are divided into bothway and unidirectional components, the division and number of circuits in each component will be agreed between Administrations.
+
+TABLE 1/F.64
+
+#### Traffic capacity table for manually selected telex circuits (Note 1)
+
+| Number of circuits | Average intensity for traffic carried in the busy hour, expressed in erlangs, for a grade of service (probability of loss) of: |                  |                  |
+|--------------------|--------------------------------------------------------------------------------------------------------------------------------|------------------|------------------|
+|                    | 1 in 10 (Note 2)                                                                                                               | 1 in 30 (Note 3) | 1 in 50 (Note 3) |
+| <i>a</i>           | <i>b</i>                                                                                                                       | <i>c</i>         | <i>d</i>         |
+| 1                  | 0.2                                                                                                                            | 0.066            | 0.034            |
+| 2                  | 0.9                                                                                                                            | 0.43             | 0.33             |
+| 3                  | 1.5                                                                                                                            | 0.89             | 0.76             |
+| 4                  | 2.3                                                                                                                            | 1.49             | 1.29             |
+| 5                  | 3.2                                                                                                                            | 2.17             | 1.92             |
+| 6                  |                                                                                                                                | 2.92             | 2.67             |
+| 7                  |                                                                                                                                | 3.77             | 3.44             |
+| 8                  |                                                                                                                                | 4.66             | 4.25             |
+| 9                  |                                                                                                                                | 5.56             | 5.09             |
+| 10                 |                                                                                                                                | 6.47             | 5.93             |
+| 11                 |                                                                                                                                | 7.39             | 6.79             |
+| 12                 |                                                                                                                                | 8.31             | 7.67             |
+| 13                 |                                                                                                                                | 9.24             | 8.57             |
+| 14                 |                                                                                                                                | 10.2             | 9.48             |
+| 15                 |                                                                                                                                | 11.1             | 10.4             |
+| 16                 |                                                                                                                                | 12.1             | 11.3             |
+| 17                 |                                                                                                                                | 13.0             | 12.3             |
+| 18                 |                                                                                                                                | 13.9             | 13.2             |
+| 19                 |                                                                                                                                | 14.9             | 14.1             |
+| 20                 |                                                                                                                                | 15.9             | 15.0             |
+
+*Note 1* – Table 1/F.64 makes allowance for the manual operator to continue the search for a free line over the group of circuits concerned for a period of 30 seconds if all are engaged, after which the search is abandoned and the call suspended.
+
+*Note 2* – Column *b* of Table 1/F.64 will, in general, only be used in respect of small groups of circuits of considerable length, having due regard to the desire to provide a rapid service, as well as to economic considerations.
+
+*Note 3* – In all other cases the figures of column *c* shall be used in preference to those of column *d*.
+
+Image: Figure 1/F.64: An example for using Table 2/F.64. The diagram shows a grid with axes for Number of circuits (N) and Availability (K). Arrows indicate the flow from the axes to the corresponding values in the table.
+
+| K \ N      | 10    | <b>[K]</b> Availability              | 50    | N     |
+|------------|-------|--------------------------------------|-------|-------|
+| <b>[N]</b> |       |                                      |       |       |
+| 100        | 64.0  |                                      | 84.1  | 88.0  |
+| 102        | 65.3  |                                      | 85.9  | 89.9  |
+| 104        | 66.5  |                                      | 87.6  | 91.9  |
+| 106        | 67.8  |                                      | 89.4  | 93.8  |
+| <b>[N]</b> |       |                                      |       |       |
+| Circuits   |       | <b>[A]</b> Traffic offered (erlangs) |       |       |
+| 196        | 125.4 |                                      | 170.4 | 182.2 |
+| 198        | 126.7 |                                      | 172.2 | 184.2 |
+| 200        | 128.0 |                                      | 174.1 | 186.2 |
+
+FIGURE 1/F.64
+
+An example for using Table 2/F.64
+
+TABLE 2/F.64
+
+#### Traffic capacity table for automatic circuits
+
+| K  | 10    | 20   | 30   | 50   | ... N |
+|----|-------|------|------|------|-------|
+| N  | <hr/> |      |      |      |       |
+|    | A     |      |      |      |       |
+| 1  |       |      |      |      | 0.02  |
+| 2  |       |      |      |      | 0.22  |
+| 3  |       |      |      |      | 0.60  |
+| 4  |       |      |      |      | 1.09  |
+| 5  |       |      |      |      | 1.66  |
+| 6  |       |      |      |      | 2.28  |
+| 7  |       |      |      |      | 2.94  |
+| 8  |       |      |      |      | 3.63  |
+| 9  |       |      |      |      | 4.34  |
+| 10 | 5.08  |      |      |      | 5.08  |
+| 11 | 5.68  |      |      |      | 5.84  |
+| 12 | 6.29  |      |      |      | 6.61  |
+| 13 | 6.90  |      |      |      | 7.40  |
+| 14 | 7.52  |      |      |      | 8.20  |
+| 15 | 8.15  |      |      |      | 9.01  |
+| 16 | 8.77  |      |      |      | 9.83  |
+| 17 | 9.40  |      |      |      | 10.7  |
+| 18 | 10.0  |      |      |      | 11.5  |
+| 19 | 10.7  |      |      |      | 12.3  |
+| 20 | 11.3  | 13.2 |      |      | 13.2  |
+| 21 | 12.0  | 13.9 |      |      | 14.0  |
+| 22 | 12.6  | 14.7 |      |      | 14.9  |
+| 23 | 13.3  | 15.4 |      |      | 15.8  |
+| 24 | 13.9  | 16.2 |      |      | 16.6  |
+| 25 | 14.6  | 16.9 |      |      | 17.5  |
+| 26 | 15.2  | 17.7 |      |      | 18.4  |
+| 27 | 15.9  | 18.4 |      |      | 19.3  |
+| 28 | 16.5  | 19.2 |      |      | 20.2  |
+| 29 | 17.2  | 19.9 |      |      | 21.0  |
+| 30 | 17.8  | 20.7 | 21.9 |      | 21.9  |
+| 31 | 18.5  | 21.5 | 22.7 |      | 22.8  |
+| 32 | 19.2  | 22.2 | 23.5 |      | 23.7  |
+| 33 | 19.8  | 23.0 | 24.3 |      | 24.6  |
+| 34 | 20.5  | 23.8 | 25.1 |      | 25.5  |
+| 35 | 21.1  | 24.6 | 26.0 |      | 26.4  |
+| 36 | 21.8  | 25.3 | 26.8 |      | 27.3  |
+| 37 | 22.5  | 26.1 | 27.6 |      | 28.3  |
+| 38 | 23.1  | 26.9 | 28.4 |      | 29.2  |
+| 39 | 23.8  | 27.7 | 29.2 |      | 30.1  |
+| 40 | 24.4  | 28.4 | 30.0 |      | 31.0  |
+| 41 | 25.1  | 29.2 | 30.8 |      | 31.9  |
+| 42 | 25.8  | 30.0 | 31.7 |      | 32.8  |
+| 43 | 26.4  | 30.8 | 32.5 |      | 33.8  |
+| 44 | 27.1  | 31.6 | 33.3 |      | 34.7  |
+| 45 | 27.8  | 32.3 | 34.1 |      | 35.6  |
+| 46 | 28.4  | 33.1 | 34.9 |      | 36.5  |
+| 47 | 29.1  | 33.9 | 35.8 |      | 37.5  |
+| 48 | 29.8  | 34.7 | 36.6 |      | 38.4  |
+| 49 | 30.4  | 35.5 | 37.4 |      | 39.3  |
+| 50 | 31.1  | 36.3 | 38.2 | 40.3 | 40.3  |
+
+TABLE 2/F.64
+
+*(cont'd)*
+
+| K   |   | 10   | 20   | 30   | 50   | ... N |
+|-----|---|------|------|------|------|-------|
+| N   |   |      |      |      |      |       |
+|     | A |      |      |      |      |       |
+| 50  |   | 31.1 | 36.3 | 38.2 | 40.3 | 40.3  |
+| 51  |   | 31.8 | 37.1 | 39.1 | 41.1 | 41.2  |
+| 52  |   | 32.4 | 37.9 | 39.9 | 42.0 | 42.1  |
+| 53  |   | 33.1 | 38.7 | 40.7 | 42.8 | 43.1  |
+| 54  |   | 33.8 | 39.4 | 41.6 | 43.7 | 44.0  |
+| 55  |   | 34.4 | 40.2 | 42.4 | 44.6 | 44.9  |
+| 56  |   | 35.1 | 41.0 | 43.2 | 45.4 | 45.9  |
+| 57  |   | 35.7 | 41.8 | 44.1 | 46.3 | 46.8  |
+| 58  |   | 36.4 | 42.6 | 44.9 | 47.2 | 47.8  |
+| 59  |   | 37.1 | 43.4 | 45.7 | 48.0 | 48.7  |
+| 60  |   | 37.7 | 44.2 | 46.6 | 48.9 | 49.6  |
+| 61  |   | 38.4 | 45.0 | 47.4 | 49.8 | 50.6  |
+| 62  |   | 39.1 | 45.8 | 48.2 | 50.6 | 51.5  |
+| 63  |   | 39.7 | 46.6 | 49.1 | 51.5 | 52.5  |
+| 64  |   | 40.4 | 47.4 | 49.9 | 52.4 | 53.4  |
+| 65  |   | 41.0 | 48.2 | 50.8 | 53.3 | 54.4  |
+| 66  |   | 41.7 | 49.0 | 51.6 | 54.1 | 55.3  |
+| 67  |   | 42.4 | 49.8 | 52.4 | 55.0 | 56.3  |
+| 68  |   | 43.0 | 50.6 | 53.3 | 55.9 | 57.2  |
+| 69  |   | 43.7 | 51.4 | 54.1 | 56.7 | 58.2  |
+| 70  |   | 44.4 | 52.2 | 55.0 | 57.6 | 59.1  |
+| 71  |   | 45.0 | 53.0 | 55.8 | 58.5 | 60.1  |
+| 72  |   | 45.7 | 53.8 | 56.6 | 59.4 | 61.0  |
+| 73  |   | 46.3 | 54.6 | 57.5 | 60.2 | 62.0  |
+| 74  |   | 47.0 | 55.4 | 58.3 | 61.1 | 62.9  |
+| 75  |   | 47.6 | 56.2 | 59.2 | 62.0 | 63.9  |
+| 76  |   | 48.3 | 57.0 | 60.0 | 62.9 | 64.9  |
+| 77  |   | 49.0 | 57.8 | 60.9 | 63.8 | 65.8  |
+| 78  |   | 49.6 | 58.6 | 61.7 | 64.6 | 66.8  |
+| 79  |   | 50.3 | 59.4 | 62.6 | 65.5 | 67.7  |
+| 80  |   | 50.9 | 60.2 | 63.4 | 66.4 | 68.7  |
+| 81  |   | 51.6 | 61.0 | 64.3 | 67.3 | 69.6  |
+| 82  |   | 52.2 | 61.8 | 65.1 | 68.2 | 70.6  |
+| 83  |   | 52.9 | 62.6 | 66.0 | 69.0 | 71.6  |
+| 84  |   | 53.6 | 63.4 | 66.8 | 69.9 | 72.5  |
+| 85  |   | 54.2 | 64.2 | 67.6 | 70.8 | 73.5  |
+| 86  |   | 54.9 | 65.0 | 68.5 | 71.7 | 74.5  |
+| 87  |   | 55.5 | 65.9 | 69.3 | 72.6 | 75.4  |
+| 88  |   | 56.2 | 66.7 | 70.2 | 73.5 | 76.4  |
+| 89  |   | 56.8 | 67.5 | 71.0 | 74.3 | 77.3  |
+| 90  |   | 57.5 | 68.3 | 71.9 | 75.2 | 78.3  |
+| 91  |   | 58.1 | 69.1 | 72.7 | 76.1 | 79.3  |
+| 92  |   | 58.8 | 69.9 | 73.6 | 77.0 | 80.2  |
+| 93  |   | 59.4 | 70.7 | 74.4 | 77.9 | 81.2  |
+| 94  |   | 60.1 | 71.5 | 75.3 | 78.8 | 82.2  |
+| 95  |   | 60.7 | 72.3 | 76.2 | 79.7 | 83.1  |
+| 96  |   | 61.4 | 73.1 | 77.0 | 80.5 | 84.1  |
+| 97  |   | 62.0 | 73.9 | 77.9 | 81.4 | 85.1  |
+| 98  |   | 62.7 | 74.7 | 78.7 | 82.3 | 86.0  |
+| 99  |   | 63.3 | 75.5 | 79.6 | 83.2 | 87.0  |
+| 100 |   | 64.0 | 76.3 | 80.4 | 84.1 | 88.0  |
+
+TABLE 2/F.64
+
+*(concluded)*
+
+| K   |   | 10    | 20    | 30    | 50    | ... N |
+|-----|---|-------|-------|-------|-------|-------|
+| N   |   |       |       |       |       |       |
+| 100 | A | 64.0  | 76.3  | 80.4  | 84.1  | 88.0  |
+| 102 |   | 65.3  | 77.9  | 82.1  | 85.9  | 89.9  |
+| 104 |   | 66.5  | 79.6  | 83.8  | 87.6  | 91.9  |
+| 106 |   | 67.8  | 81.2  | 85.5  | 89.4  | 93.8  |
+| 108 |   | 69.1  | 82.8  | 87.3  | 91.2  | 95.7  |
+| 110 |   | 70.4  | 84.4  | 89.0  | 93.0  | 97.7  |
+| 112 |   | 71.7  | 86.0  | 90.7  | 94.8  | 99.6  |
+| 114 |   | 72.9  | 87.6  | 92.4  | 96.6  | 101.6 |
+| 116 |   | 74.2  | 89.3  | 94.1  | 98.3  | 103.5 |
+| 118 |   | 75.5  | 90.9  | 95.8  | 100.1 | 105.5 |
+| 120 |   | 76.8  | 92.5  | 97.5  | 101.9 | 107.4 |
+| 122 |   | 78.1  | 94.1  | 99.3  | 103.7 | 109.4 |
+| 124 |   | 79.3  | 95.7  | 101.0 | 105.5 | 111.3 |
+| 126 |   | 80.6  | 97.3  | 102.7 | 107.3 | 113.3 |
+| 128 |   | 81.9  | 99.0  | 104.4 | 109.1 | 115.2 |
+| 130 |   | 83.2  | 100.6 | 106.1 | 110.9 | 117.2 |
+| 132 |   | 84.5  | 102.2 | 107.9 | 112.7 | 119.1 |
+| 134 |   | 85.7  | 103.8 | 109.6 | 114.5 | 121.1 |
+| 136 |   | 87.0  | 105.4 | 111.3 | 116.3 | 123.1 |
+| 138 |   | 88.3  | 107.0 | 113.0 | 118.1 | 125.0 |
+| 140 |   | 89.6  | 108.7 | 114.7 | 119.9 | 127.0 |
+| 142 |   | 90.8  | 110.3 | 116.5 | 121.7 | 128.9 |
+| 144 |   | 92.1  | 111.9 | 118.2 | 123.5 | 130.9 |
+| 146 |   | 93.4  | 113.5 | 119.9 | 125.3 | 132.9 |
+| 148 |   | 94.7  | 115.1 | 121.6 | 127.1 | 134.8 |
+| 150 |   | 96.0  | 116.7 | 123.4 | 128.9 | 136.8 |
+| 152 |   | 97.2  | 118.3 | 125.1 | 130.7 | 138.8 |
+| 154 |   | 98.5  | 120.0 | 126.8 | 132.5 | 140.7 |
+| 156 |   | 99.8  | 121.6 | 128.5 | 134.3 | 142.7 |
+| 158 |   | 101.1 | 123.2 | 130.3 | 136.1 | 144.7 |
+| 160 |   | 102.4 | 124.8 | 132.0 | 137.9 | 146.6 |
+| 162 |   | 103.6 | 126.4 | 133.7 | 139.7 | 148.6 |
+| 164 |   | 104.9 | 128.0 | 135.4 | 141.5 | 150.6 |
+| 166 |   | 106.2 | 129.6 | 137.2 | 143.3 | 152.6 |
+| 168 |   | 107.5 | 131.2 | 138.9 | 145.1 | 154.5 |
+| 170 |   | 108.8 | 132.9 | 140.6 | 146.9 | 156.5 |
+| 172 |   | 110.0 | 134.5 | 142.3 | 148.7 | 158.5 |
+| 174 |   | 111.3 | 136.1 | 144.1 | 150.5 | 160.4 |
+| 176 |   | 112.6 | 137.7 | 145.8 | 152.3 | 162.4 |
+| 178 |   | 113.9 | 139.3 | 147.5 | 154.1 | 164.4 |
+| 180 |   | 115.2 | 140.9 | 149.2 | 155.9 | 166.4 |
+| 182 |   | 116.4 | 142.5 | 151.0 | 157.7 | 168.3 |
+| 184 |   | 117.7 | 144.1 | 152.7 | 159.6 | 170.3 |
+| 186 |   | 119.0 | 145.7 | 154.4 | 161.4 | 172.3 |
+| 188 |   | 120.3 | 147.3 | 156.2 | 163.2 | 174.3 |
+| 190 |   | 121.6 | 148.9 | 157.9 | 165.0 | 176.3 |
+| 192 |   | 122.8 | 150.6 | 159.6 | 166.8 | 178.2 |
+| 194 |   | 124.1 | 152.2 | 161.3 | 168.6 | 180.2 |
+| 196 |   | 125.4 | 153.8 | 163.1 | 170.4 | 182.2 |
+| 198 |   | 126.7 | 155.4 | 164.8 | 172.2 | 184.2 |
+| 200 |   | 128.0 | 157.0 | 166.5 | 174.1 | 186.2 |

marked/F/T-REC-F.65-198811-I_PDF-E/raw.md

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt striking through it, and the letters 'ITU' superimposed on the globe.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.65**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**OPERATIONS AND QUALITY OF SERVICE  
+TELEGRAPH SERVICES**
+
+---
+
+**TIME - TO - ANSWER BY OPERATORS  
+AT INTERNATIONAL TELEX POSITIONS**
+
+**ITU-T Recommendation F.65**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1          ITU-T Recommendation F.65 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2          In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **Recommendation F.65**
+
+## **TIME-TO-ANSWER BY OPERATORS AT INTERNATIONAL TELEX POSITIONS**
+
+The CCITT,
+
+*considering*
+
+- (a) that a rapid answer to calling signals by the operators at incoming international telex positions is essential to ensure a rapid telex service;
+- (b) that a rapid answer is a very important factor in the efficient utilization of international telex circuits;
+- (c) that the time-to-answer has a direct effect on the costs of staffing and of switchboard provision;
+
+*unanimously declares*
+
+that, wherever possible, Administrations should give priority to the answering of incoming calling signals at international terminal exchanges and should endeavour to ensure that 95% of calls are answered within 30 seconds.

marked/F/T-REC-F.69-199406-I_PDF-E/raw.md

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.69**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(06/94)
+
+# **OPERATIONS AND QUALITY OF SERVICE TELEGRAPH SERVICES** ---
+
+# **THE INTERNATIONAL TELEX SERVICE – SERVICE AND OPERATIONAL PROVISIONS OF TELEX DESTINATION CODES AND TELEX NETWORK IDENTIFICATION CODES**
+
+**ITU-T Recommendation F.69**
+
+(Previously "CCITT Recommendation")
+
+---
+
+## FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation F.69 was revised by ITU-T Study Group 1 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 1st of June 1994.
+
+---
+
+## NOTE
+
+In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## CONTENTS
+
+|                                                                   | <i>Page</i> |
+|-------------------------------------------------------------------|-------------|
+| 1 Introduction .....                                              | 1           |
+| 2 Scope .....                                                     | 1           |
+| 3 List of associated Recommendations .....                        | 1           |
+| 4 Definitions.....                                                | 1           |
+| 5 Functions of the Telex Destination Code .....                   | 1           |
+| 6 General principles of structure of telex destination code ..... | 2           |
+| 7 Structure of the telex network identification code .....        | 3           |
+| 8 Procedures for allocation of codes .....                        | 4           |
+
+# **SUMMARY**
+
+The interconnection of the networks of the countries and recognized operating agencies participating in the international telex service requires the development of a standardized mechanism for the routing of calls between subscribers in a transparent manner. This is achieved through the use of a telex destination code which is used for routing purposes in international exchanges. Telex destination codes may also be used within national telex networks or at international gateway exchanges for recording call details for billing and accounting purposes, or sometimes for other purposes such as segregating particular types of traffic. Furthermore, the service requirement enabling the identification of the called subscriber and thereby giving assurance of correct connection is achieved by the inclusion of a telex network identification code in the answerbacks of subscribers of the international telex service in addition to the subscribers national telex number.
+
+This Recommendation describes the procedures to be followed in the allocation of telex destination codes and telex network identification codes. The means of promulgation publication, and date of entry into effect of code allocations are also identified.
+
+## **THE INTERNATIONAL TELEX SERVICE – SERVICE AND OPERATIONAL PROVISIONS OF TELEX DESTINATION CODES AND TELEX NETWORK IDENTIFICATION CODES**
+
+*(revised, 1994)*
+
+## **1 Introduction**
+
+The interconnection of the networks of the countries and recognized operating agencies (ROA) participating in the international telex service requires the development of a standardized mechanism for the routing of calls between subscribers in a transparent manner. This is achieved through the use of a telex destination code which is used for routing purposes in international exchanges. Telex destination codes may also be used within national telex networks or at international gateway exchanges for recording call details for billing and accounting purposes, or sometimes for other purposes such as segregating particular types of traffic. Furthermore, the service requirement enabling the identification of the called subscriber and thereby giving assurance of correct connection is achieved by the inclusion of a telex network identification code in the answerbacks of subscribers of the international telex service in addition to the subscribers national telex number.
+
+## **2 Scope**
+
+This Recommendation describes the procedures to be followed in the allocation of telex destination codes and telex network identification codes. The means of promulgation, publication, and date of entry into effect of code allocations are also identified.
+
+## **3 List of associated Recommendations**
+
+This Recommendation should be read in association with the following Recommendations:
+
+- Recommendation F.31 *Telegram Retransmission System.*
+- Recommendation F.59 *General Characteristics of the International Telex Service.*
+- Recommendation F.60 *Operational Provisions for the International Telex Service.*
+- Recommendation F.68 *Establishment of the automatic Intercontinental Telex Network.*
+- Recommendation F.96 *Telegram Destination Indicators.*
+- Recommendation R.79 *Automatic Tests of Transmission Quality on Telegraph Circuits between Switching Centres.*
+- Recommendation U.7 *Numbering Schemes for Automatic Switching networks.*
+- Recommendation U.11 *Telex and Gentex Signalling on Intercontinental Circuits used for Intercontinental Automatic Transit Traffic (Type C Signalling).*
+- Recommendation U.74 *Extraction of Telex Selection Information from a Calling Telex Answerback.*
+
+## **4 Definitions**
+
+The terms “telex destination code” and “telex network identification code” are defined in Recommendation F.68.
+
+## **5 Functions of the Telex Destination Code**
+
+**5.1** There are many Recommendations dealing with the international telex service, several of them being many years in existence. In all cases, reference to “telex” needs to be understood to refer exclusively to the international telex service which is described in Recommendations F.59 and F.60.
+
+**5.2** Recommendation F.60 states that “The networks of the countries participating in the international telex service shall, as far as possible, be directly connected and shall thereby constitute the international telex network”. The telex destination codes referenced in this Recommendation are, therefore, primarily used for routing purposes within international telex exchanges within the originating network and any transit network, but see also clause 1. In accordance with U-Series signalling Recommendations, the destination network may also request the receipt of the complete international telex number (which includes the telex destination code) on terminating traffic.
+
+**5.3** Any revision to an existing code allocation requires adjustments to be made normally not in the network which has requested the change/allocation but in all other networks which comprise the international telex network. Accordingly, this procedure results in telex destination codes being of relevance primarily to originating and transit networks, and only rarely to destination networks. As the international telex service is now recognised as a mature service having evolved over many years, and some networks may use spare codes for purposes other than as stated herein, caution needs to be exercised in the future allocation of codes for emerging new networks.
+
+**5.4** One of the unique characteristics of the international telex service is the ability to assure connection to the addressed party through the automatic return of the called subscriber answerback sequence on call set-up. The format of the answerback is specified in Recommendation F.60. This standardized structure is also used to determine the (recall) telex address by an analysis of the answerback of the calling telex subscriber in accordance with the rules laid down in Recommendation U.74 when messages are being forwarded either via a store and forward unit or in some interworking cases. Therefore, there is a firm requirement for a telex network identification code to be always associated with a telex destination code in order to fully characterize the network of any telex subscriber.
+
+**5.5** For operational reasons, unallocated telex destination codes are sometimes used by ROAs for both national and international applications, the latter being on the basis of bilateral agreement or multilateral agreement(s). While the use of such codes internationally is discouraged except in the case of temporary expediency, such use, as well as ROAs' national applications, should be taken into account when selecting new codes for allocation.
+
+## **6 General principles of structure of telex destination code**
+
+**6.1** The U-Series signalling Recommendations permit a maximum of 12 selection digits to be signalled across an international link. Accordingly, in establishing the initial plan for telex destination codes, it was necessary to decide whether these codes should always comprise three digits, or whether they could be made up of two or three digits.
+
+**6.2** The advantages of uniform three-digit codes were seen to be:
+
+- i) by allocating the same size code to all countries, difficulties would not arise as to the relative importance of the various countries with regard to the international telex service;
+- ii) uniform codes afford some simplification of the design of exchanges;
+- iii) for the European system a uniform three-digit system could be readily compiled by adding a uniform digit to the range of two-digit codes already in use at the time by a number of European Administrations.
+
+**6.3** The advantages of a mixed two or three-digit arrangement were seen to be:
+
+- i) the use of shorter length codes reduced the risk of errors by calling subscribers;
+- ii) the storage capacity of registers could be kept to a minimum by allocating shorter codes to systems having long subscribers' numbers;
+- iii) the holding time of circuits could be kept to a minimum;
+- iv) the maximum number of digits to be examined for routing and other purposes could be kept to a minimum by allocating shorter codes to systems in which the first two digits of a subscriber's number have to be examined in accordance with Recommendation U.7. Similarly, where a country had more than one international exchange the allocation of a shorter code would enable the routing of traffic to be controlled by the examination of a minimum number of digits.
+
+**6.4** A mixed environment of two-digit and three-digit destination codes was seen to have the most advantages, and was adopted as the basis for this Recommendation.
+
+**6.5** The following principles apply to the allocation of the first digit:
+
+0 – not to be used as first digit;
+
+1 – see 6.8 and 6.9;
+
+2 – North America and adjacent areas;
+
+3 – South America and adjacent areas;
+
+4 – Europe and adjacent areas;
+
+5 – Europe and adjacent areas and maritime-satellite services;
+
+6 – Europe and adjacent areas;
+
+7 – Pacific and adjacent areas;
+
+8 – Middle East, Far East and adjacent areas;
+
+9 – Africa, Near East and adjacent areas.
+
+## NOTES
+
+1 The geographical boundaries of the continents have not been rigidly followed to permit maximum flexibility within the code system.
+
+2 In relations using Type C signalling (see Recommendation U.11) code 000 may be used for retest signalling purposes in accordance with Recommendation R.79.
+
+3 In case of the assignment of codes to a maritime mobile-satellite system, a three-digit code could exceptionally be assigned to each ocean area of the satellite system.
+
+**6.6** The number of two-digit codes available is rather restricted. It is undesirable to allocate these to serve individual networks in countries where several networks exist but do not have a co-ordinated internal numbering scheme;
+
+**6.7** It is not advisable to allocate all possible two-digit codes, so as to maintain some flexibility to allow future development to be taken into account. Accordingly, all new allocations will be of three digits in order to maximise the use of the available spare telex destination codes.
+
+**6.8** The first digit 1 was initially reserved for special services, which led to its uncoordinated use in a variety of national and international applications in different networks. In all future networks and as soon as practicable in existing networks, it should be possible to allocate the 1 series for destination codes for international purposes.
+
+**6.9** A block of ten destination codes (160-169) has been set aside to cover the particular needs for access to maritime mobile HF and MF radiotelex services. The choice of code or codes for these applications is left to individual ROAs for use by their own subscribers and/or (after suitable bilateral arrangements have been reached) by subscribers of other ROAs for transit calls.
+
+NOTE – It is recognized that some ROAs use various codes in the 160-169 series at present for national and international applications.
+
+## **7 Structure of the telex network identification code**
+
+**7.1** The telex network identification code (TNIC) consists of either one or two letters in accordance with Recommendation F.68.
+
+**7.2** In the case of two-letter TNICs, the code should be the same as the first two characters of the destination indicator of their country or network for the telegram retransmission system in accordance with Recommendation F.31, as noted in Recommendations F.68 and F.96.
+
+**7.3** In principle, no further single-letter TNICs should be allocated.
+
+## 8 Procedures for allocation of codes
+
+8.1 The Administration of a ROA wishing to take part in the international automatic telex service should apply to the Director of the TSB for the assignment of an *available* three-digit destination code and a two-letter TNIC. In its request, it may indicate the available three-digit code preferred. Where the numbering scheme for the appropriate region is exhausted, a code from a proximate region may be allocated.
+
+8.2 In all cases, such requests should be referred to the Chairman of Study Group 1 for guidance on technical and operational issues, taking account of possible future requirements. The procedures to be followed are given in Figure 1.
+
+8.3 It is the responsibility of the TSB:
+
+- to carry out the necessary discussion with the applicant Administration;
+- to ensure that the Chairman of Study Group 1 is satisfied that any technical and operational requirements have been covered before final allocation of the relevant destination and network identification codes.
+
+8.4 Additions and changes that are accepted will be published in the ITU *Operational Bulletin*. They will become effective on the first day of the third month following publication.
+
+8.5 The list of allocated and spare telex destination codes, including the corresponding telex network identification codes, will be published periodically in the *Operational Bulletin*.
+
+![Flowchart for the allocation and publication of telex destination codes and telex network identification codes. The process starts with a request received in TSB, followed by discussions, passing details to Study Group 1, seeking guidance from expert groups, identifying issues, replying to TSB, reaching an agreement, informing the applicant, and finally publishing the updated list. There are feedback loops to discussions at various stages.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+```
+
+graph TD
+    A[Request received in TSB for allocation/change of code(s)] --> B[Details passed by TSB to Study Group 1 Chairman a)]
+    B --> C[Study Group 1 Chairman a) seeks guidance from Study Group 1 expert group(s) on proposal b)]
+    C --> D{Have any technical/ operational issues been identified by expert group?}
+    D -- Yes --> E[Study Group 1 Chairman a) reverts to TSB with guidance on resolution of any identified operational or technical issues]
+    D -- No --> F[Study Group 1 Chairman a) replies accordingly to the TSB]
+    E --> G[TSB/Applicant discussions]
+    G --> H{Agreement?}
+    H -- Yes --> I[TSB informs applicant and announces code allocation in Operational Bulletin]
+    H -- No --> J[Relevant Study Group 1 expert group to inform the next meeting of Study Group 1 (Working Party) on work]
+    I --> K[TSB to publish updated list of allocated and spare codes periodically in Operational Bulletin]
+    J --> A
+    G --> A
+    E -.->|Normally 15 working days|> G
+  
+```
+
+T0103390-94/d01
+
+a) Or Chairman's delegated representative.  
+ b) To be done in consultation with expert group nominated by Study Group 1 for such tasks.
+
+Flowchart for the allocation and publication of telex destination codes and telex network identification codes. The process starts with a request received in TSB, followed by discussions, passing details to Study Group 1, seeking guidance from expert groups, identifying issues, replying to TSB, reaching an agreement, informing the applicant, and finally publishing the updated list. There are feedback loops to discussions at various stages.
+
+FIGURE 1/F.69  
+**Scheme for the allocation and publication of telex destination codes and telex network identification codes**

marked/F/T-REC-F.70-198811-I_PDF-E/raw.md

@@ -0,0 +1,176 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. A lightning bolt symbol is positioned to the right of the globe.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.70**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**OPERATIONS AND QUALITY OF SERVICE  
+TELEGRAPH SERVICES**
+
+---
+
+**EVALUATING THE QUALITY OF  
+THE INTERNATIONAL TELEX SERVICE**
+
+**ITU-T Recommendation F.70**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation F.70 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## **EVALUATING THE QUALITY OF THE INTERNATIONAL TELEX SERVICE**
+
+## **1 Introduction**
+
+1.1 The Quality of Service is a measure of the perceived performance of the telex network. The perception of the service performance varies between that of the calling subscriber, the origin Administration, the destination Administration and the called subscriber. For example, national network difficulties in reaching the origin international exchange will usually be noticed only by the calling subscriber. However, if the origin or destination Administration automatically retries to reach the wanted subscriber following an unsuccessful call attempt, these reattempts are not seen by that part of the network that precedes it. Conversely, a called subscriber is unaware of the number of times that call attempts are being made to his number, if his machine is busy or out of order.
+
+1.2 The main criteria of service performance from the users' viewpoint are:
+
+- a) the ease in establishing a connection;
+- b) the retention of the established connection;
+- c) the satisfactory transmission quality;
+- d) the integrity of billing.
+
+1.3 Where possible, the critical areas of service performance should be measured in a manner that provides both origin and destination Administrations with comparable data. For example, arrangements to ensure concurrency of the periods of observation by the two Administrations involved in each given relation is of great importance. These measurement should, if possible, show the performance as perceived in the originating network and in the destination network.
+
+1.4 Where a subscriber number is found to be "hard to reach" (HTR), then, if possible, this number should be separately identified to allow the origin and destination Administrations mutually to analyze the cause of the problem.
+
+## **2 Method of measuring quality of service**
+
+2.1 Administrations should draw up a programme for telex observations designed to evaluate the quality of the service given to subscribers in their automatic and semi-automatic international services.
+
+2.2 Where Administrations have equipment that automatically records details of calls, this information may be used to compile details of network performance.
+
+2.3 In order to provide compatible data between the origin and destination networks, where possible, Administrations should measure the perceived performance in the origin network (e.g., at the entry point to the international gateway exchange if applicable) in addition to the performance at the international interface looking towards the destination network.
+
+## **3 Analysis of results**
+
+3.1 Administrations should exchange data on a bilaterally agreed basis, commensurate with their operational requirements and, in principle, at least once every six months.
+
+3.2 The results may then be analyzed as shown below (see also Table 1/F.70):
+
+- a) Check effective rate to the destination compared with the average to all destinations.
+- b) Check the current rate versus the performance as measured in the past.
+- c) Check the performance with results obtained by other Administrations to the same destination.
+- d) If the performance has suddenly degraded, perform a detailed analysis where possible, monitor circuit group performance and analyze the performance on a destination code basis. The degradation on a circuit group could be caused by a faulty circuit which, when seized, fails to successfully switch a call.
+
+3.3 Administrations should investigate any HTR report (greater than 50 unsuccessful attempts to one number within a day could be defined as being HTR).
+
+3.3.1 Where national regulatory arrangements allow, Administrations should check that automatic terminal equipment complies with Recommendation U.40. Where poor terminal operating procedures exist, customers should be referred to the guidelines annexed to Recommendation F.60.
+
+3.3.2 The destination Administration should proceed as follows:
+
+3.3.2.1 **OCC** : the called subscriber should be advised that his telex machine is very busy and that extra machines (or terminations) may be necessary.
+
+3.3.2.2 **DER** : is this still a working service? If not, the service signal should be changed to **NP** or **NCH**. If the service is still working, the customer should be asked if the machine is being disabled, e.g., by switching off the power. If a computer interface is being used, is the telex machine being correctly switched in when the computer is taken off-line?
+
+3.3.2.3 **NP/NCH** : consult the origin Administration and ask it to take the matter up with the calling subscriber.
+
+3.3.2.4 Answerback failure:
+
+- a) Where answerback failure occurs, the reasons should be investigated by the destination Administration.
+- b) Where a calling automatic terminal fails to interpret the answerback correctly, the reasons should be investigated by the origin Administration.
+
+3.4 Where possible, Administrations should also investigate and report as necessary when frequent cases of clearing from the destination network occurs after charging commences, since a likely cause in such cases is a transmission fault during the text transmission.
+
+3.5 Regular discussion should take place with other Administrations, on a bilateral basis, with a view towards improving the mutual network performance.
+
+## 4 Explanation of terms used in Table 1/F.70
+
+### 4.1 *Effective call*
+
+An effective call is defined as a call for which a charge was made or that was successfully completed to a service position. Where possible, measurements should be corrected to take account of any calls for which the charge has been adjusted.
+
+### 4.2 *Ineffective call*
+
+Any calls or call attempts that did not result in an effective call.
+
+### 4.3 *Chargeable time*
+
+Duration between the call-connected signal and recognition of the clearing of a call, less 5 to 7 seconds (see Recommendation F.61).
+
+### 4.4 *Call set-up time*
+
+The time between circuit seizure and the receipt of a call-connected or service signal. This time will not be the same on the national and the international sides of the exchange.
+
+### 4.5 *PTS failure*
+
+The proceed-to-select signal has not been received within a nominated period after a call signal has been sent to the next exchange.
+
+### 4.6 *Service signals*
+
+(ABS, DER, NA, NC, NCH, NP, OCC) are defined in Recommendation F.60, § 4.1.
+
+TABLE 1/F.70
+
+#### **International telex service observations**
+
+ADMINISTRATION:
+
+TRAFFIC OUTGOING FROM: TO
+
+PERIOD OF OBSERVATION: UTC TO UTC
+
+ROUTE BUSY HOUR: UTC TO UTC
+
+| Number of observations                                  |                                          | Point of observation     |                          |                          |                          |
+|---------------------------------------------------------|------------------------------------------|--------------------------|--------------------------|--------------------------|--------------------------|
+| National side                                           | International side<br>(Includes retries) | National side            |                          | International side       |                          |
+|                                                         |                                          | Average this destination | Average all destinations | Average this destination | Average all destinations |
+| Effective calls                                         | Percentage                               |                          |                          |                          |                          |
+|                                                         | Chargeable time (min. sec.)              |                          |                          |                          |                          |
+|                                                         | Call setup time (min. sec.)              |                          |                          |                          |                          |
+| Ineffective calls                                       | Percentage                               |                          |                          |                          |                          |
+|                                                         | Call setup time (min. sec.)              |                          |                          |                          |                          |
+| Analysis of ineffective calls (Expressed as percentage) |                                          |                          |                          |                          |                          |
+| Outgoing circuit selected                               | PTS Failure                              |                          |                          |                          |                          |
+|                                                         | OCC Signal received                      |                          |                          |                          |                          |
+|                                                         | DER Signal received                      |                          |                          |                          |                          |
+|                                                         | NP Signal received                       |                          |                          |                          |                          |
+|                                                         | ABS Signal received                      |                          |                          |                          |                          |
+|                                                         | NC Signal from distant network           |                          |                          |                          |                          |
+|                                                         | NA Signal received                       |                          |                          |                          |                          |
+|                                                         | NCH Signal received                      |                          |                          |                          |                          |
+|                                                         | Other service signals                    |                          |                          |                          |                          |
+|                                                         | No answer back after call connect        |                          |                          |                          |                          |
+|                                                         | Clear by caller before call connect      |                          |                          |                          |                          |
+|                                                         | No call connect (time out)               |                          |                          |                          |                          |
+|                                                         | Cut off during call setup                |                          |                          |                          |                          |
+|                                                         | Wrong number reached                     |                          |                          |                          |                          |
+|                                                         | Others (specify)                         |                          |                          |                          |                          |
+| No outgoing circuit selected                            | Incomplete number                        |                          |                          |                          |                          |
+|                                                         | Clearing before complete number          |                          |                          |                          |                          |
+|                                                         | Lack of outgoing circuits                |                          |                          |                          |                          |
+
+THE FOLLOWING NUMBERS WERE IDENTIFIED AS HARD TO REACH TELEX SUBSCRIBERS:  
+ SERVICE SIGNAL RECEIVED ON INTERNATIONAL SIDE
+
+| Called number | OCC | DER | ABS | NS | Others (specify) |
+|---------------|-----|-----|-----|----|------------------|
+|               |     |     |     |    |                  |
+|               |     |     |     |    |                  |
+|               |     |     |     |    |                  |
+|               |     |     |     |    |                  |
+|               |     |     |     |    |                  |
+|               |     |     |     |    |                  |
+|               |     |     |     |    |                  |
+
+*Note – An explanation of terms is given in § 4.*

marked/F/T-REC-F.701-200011-I_PDF-E/raw.md

@@ -0,0 +1,415 @@
+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.701**
+
+(11/2000)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Audiovisual services
+
+---
+
+**Guideline Recommendation for identifying  
+multimedia service requirements**
+
+ITU-T Recommendation F.701
+
+(Formerly CCITT Recommendation)
+
+---
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+### **TELEGRAPH SERVICE**
+
+|                                                                 |             |
+|-----------------------------------------------------------------|-------------|
+| Operating methods for the international public telegram service | F.1–F.19    |
+| The gentex network                                              | F.20–F.29   |
+| Message switching                                               | F.30–F.39   |
+| The international telemessage service                           | F.40–F.58   |
+| The international telex service                                 | F.59–F.89   |
+| Statistics and publications on international telegraph services | F.90–F.99   |
+| Scheduled and leased communication services                     | F.100–F.104 |
+| Phototelegraph service                                          | F.105–F.109 |
+
+## **MOBILE SERVICE**
+
+|                                                         |             |
+|---------------------------------------------------------|-------------|
+| Mobile services and multidestination satellite services | F.110–F.159 |
+|---------------------------------------------------------|-------------|
+
+### **TELEMATIC SERVICES**
+
+|                                           |             |
+|-------------------------------------------|-------------|
+| Public facsimile service                  | F.160–F.199 |
+| Teletex service                           | F.200–F.299 |
+| Videotex service                          | F.300–F.349 |
+| General provisions for telematic services | F.350–F.399 |
+
+### **MESSAGE HANDLING SERVICES**
+
+F.400–F.499
+
+## **DIRECTORY SERVICES**
+
+F.500–F.549
+
+### **DOCUMENT COMMUNICATION**
+
+|                                      |             |
+|--------------------------------------|-------------|
+| Document communication               | F.550–F.579 |
+| Programming communication interfaces | F.580–F.599 |
+
+### **DATA TRANSMISSION SERVICES**
+
+F.600–F.699
+
+### **AUDIOVISUAL SERVICES**
+
+**F.700–F.799**
+
+## **ISDN SERVICES**
+
+F.800–F.849
+
+## **UNIVERSAL PERSONAL TELECOMMUNICATION**
+
+F.850–F.899
+
+### **HUMAN FACTORS**
+
+F.900–F.999
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **Guideline Recommendation for identifying multimedia service requirements**
+
+## **Summary**
+
+This Recommendation provides guidelines for describing user requirements that are to be used as the basis for constructing new multimedia services. These guidelines are primarily intended to support the Multimedia service development methodology described in ITU-T Recommendation F.700. However, they can also be used as the basis for a structured dialogue between End-Users and Service Providers in order to arrive at a responsive service solution when applicable ITU-T service Recommendations are not yet available.
+
+## **Source**
+
+ITU-T Recommendation F.701 was prepared by ITU-T Study Group 16 (2001-2004) and was approved under the World Telecommunication Standardization Assembly Resolution No. 1 procedure on 17 November 2000.
+
+# FOREWORD
+
+ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSA Resolution No. 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 2001
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU.
+
+# CONTENTS
+
+|                                                                | Page |
+|----------------------------------------------------------------|------|
+| 1 Scope.....                                                   | 1    |
+| 2 Definitions .....                                            | 1    |
+| 3 Multimedia service development methodology.....              | 1    |
+| 3.1 Application scripts .....                                  | 2    |
+| 3.2 Communication capabilities .....                           | 2    |
+| 3.3 Middleware service elements.....                           | 2    |
+| 3.4 Multimedia service Recommendations.....                    | 2    |
+| 4 Application Scripts .....                                    | 2    |
+| 4.1 Introduction.....                                          | 2    |
+| 4.2 Prose description.....                                     | 3    |
+| 4.3 Functional model of an application.....                    | 3    |
+| 4.4 Application matrix .....                                   | 4    |
+| 4.5 Summary.....                                               | 4    |
+| 5 Harmonization of Application Scripts with other bodies ..... | 4    |
+| Appendix I – Definitions.....                                  | 5    |
+| Appendix II – Multimedia medical consultation.....             | 5    |
+| II.1 Prose Description.....                                    | 5    |
+| II.2 Application Scenario.....                                 | 5    |
+| II.2.1 Full multimedia support capability.....                 | 6    |
+| II.2.2 Restricted multimedia support capability .....          | 6    |
+| II.3 Implementation notes.....                                 | 7    |
+| II.3.1 Related applications.....                               | 7    |
+| II.3.2 Associated applications .....                           | 7    |
+| II.3.3 Security/privacy .....                                  | 7    |
+| II.3.4 Service flexibility.....                                | 8    |
+| II.3.5 Performance trade-offs .....                            | 8    |
+
+
+
+## **Guideline Recommendation for identifying multimedia service requirements**
+
+# **1 Scope**
+
+This Recommendation provides guidelines for describing user requirements that are to be used as the basis for constructing new multimedia services. These guidelines are primarily intended to support the Multimedia service development methodology described in ITU-T Recommendation F.700. However, they can also be used as the basis for a structured dialogue between End-Users and Service Providers in order to arrive at a responsive service solution when applicable ITU-T service Recommendations are not yet available.
+
+# **2 Definitions**
+
+For the purpose of this ITU-T Recommendation the terms defined in Recommendation F.700 will apply. The definitions of some important terms are reproduced in Appendix I for user convenience.
+
+# **3 Multimedia service development methodology**
+
+A detailed methodology for developing Multimedia services is described in Recommendation F.700. Figure 1 provides an overview of this methodology and shows how end-user requirements are inserted into the service development process through the use of Application Scripts. The construction of these Scripts from End-User requirements is described in the remaining clauses of this Recommendation.
+
+![Figure 1/F.701 – Multimedia service development methodology flowchart](9791722d75115ddcc599b07d7bc35d73_img.jpg)
+
+The diagram illustrates the multimedia service development methodology. At the center is an oval labeled "Service description process". To its left, a box labeled "Middleware Service Elements" has an arrow pointing to the central process. Above the central process, a stack of three boxes labeled "Application scripts" has an arrow pointing down to the process. Below the central process, a box labeled "Description of communication capabilities" has an arrow pointing up to the process. This box contains two sub-boxes: "Communication Tasks" and "Media Components". To the right of the central process, an arrow points to a box labeled "Generic multimedia service Recommendations". Above this box is a stack of three boxes labeled "F.Mxx", "F.MDS", and "F.MCS". The text "T0106070-00" is located below the "Generic multimedia service Recommendations" box.
+
+Figure 1/F.701 – Multimedia service development methodology flowchart
+
+**Figure 1/F.701 – Multimedia service development methodology**
+
+## **3.1 Application scripts**
+
+An application script is a document that describes the essential characteristics of an End-User application so as to facilitate identification and evaluation of the multimedia communication capabilities required to support it. The script, when properly validated, provides the baseline requirements for new multimedia services. The procedure for developing and validating application scripts is described in clause 4.
+
+## **3.2 Communication capabilities**
+
+Communication capabilities are the fundamental sets of communication tasks, media components and integration mechanisms required to develop the complex spectrum of multimedia services. The procedure for translating the application script into the required communications capabilities is described in ITU-T Recommendation F.700. Procedures are also identified for launching the development of new communications capabilities when required to more fully support emerging user needs.
+
+## **3.3 Middleware service elements**
+
+The middleware service elements contain all the control features and the processing functions associated with the service. They interact with the various communication capabilities in order to control them or to process the user information.
+
+## **3.4 Multimedia service Recommendations**
+
+The translation of a particular application script into a description of the required multimedia service can be accomplished directly from the basic communication capabilities by utilizing the procedures specified in ITU-T Recommendation F.700. However, this process can be simplified in many cases by recognizing that a significant number of end-user applications utilize just a few combinations of multimedia communication means. The methodology for describing these generic service architectures in a series of general ITU-T service Recommendations is also described in ITU-T Recommendation F.700.
+
+# **4 Application Scripts**
+
+## **4.1 Introduction**
+
+An application script describes the essential characteristics of an end-user application in a manner designed to facilitate identification and evaluation of the required multimedia communications support capabilities. This is accomplished by first describing the application from the end user's point of view and then translating this description into a form more useful for technical evaluation. The procedures for constructing an application script are described in 4.2 through 4.4.
+
+Ideally, an application selected for the scripting process should represent a broad grouping of individual end-user applications which have the same essential functional characteristics and for which there appears to be a need for the development of a new multimedia service, service arrangement or enhanced service capability.
+
+Differences between specific applications within this broad grouping can be represented by the specific values assigned to a particular requirement attribute. Examples are shown in 4.4. The procedures for validating the results of the scripting process are described in clause 5.
+
+## 4.2 Prose description
+
+The prose description of an application provides a comprehensive statement of its scope and functional characteristics, together with the user's expectations for the quality of service. This description is written in a language understandable to the end user, who need not be aware of the technical aspects of the underlying service or supporting communications networks.
+
+The prose description may be augmented by an application scenario and a set of implementation notes which further describe the application, highlighting those aspects which might otherwise remain unclear. A sample prose description, with associated application scenario and implementation notes, is provided in Appendix I.
+
+## 4.3 Functional model of an application
+
+The functional model provides a pictorial representation of the essential functional elements identified in the prose description. This representation is presented from the perspective of the application, rather than from the supporting service or network, and contains only those elements visible to the end user. Figure 2 provides the functional model for the prose description contained in Appendix II.
+
+![Figure 2/F.701 – A sample functional model of an application (medical consultation). The diagram shows a central 'Shared information space' rectangle connected to three 'Consultant' circles (1, 2, 3) above it, an 'Initiator' circle below it, and four external entities: 'Public medical information database' (left), 'Public medical records database' (right), 'Billing' (bottom-left), and 'Archival' (bottom-right). Arrows indicate bidirectional interactions between the central space and each entity.](367926125450c2bc3f4bdca9d59a62ba_img.jpg)
+
+```
+graph TD; C1((Consultant 1)) <--> SIS[Shared information space]; C2((Consultant 2)) <--> SIS; C3((Consultant 3)) <--> SIS; SIS <--> P1[Public medical information database]; SIS <--> P2[Public medical records database]; SIS <--> B[Billing]; SIS <--> I((Initiator)); SIS <--> A[Archival];
+```
+
+T0106080-00
+
+Figure 2/F.701 – A sample functional model of an application (medical consultation). The diagram shows a central 'Shared information space' rectangle connected to three 'Consultant' circles (1, 2, 3) above it, an 'Initiator' circle below it, and four external entities: 'Public medical information database' (left), 'Public medical records database' (right), 'Billing' (bottom-left), and 'Archival' (bottom-right). Arrows indicate bidirectional interactions between the central space and each entity.
+
+**Figure 2/F.701 – A sample functional model of an application (medical consultation)**
+
+The principle characteristics to be depicted in the model are:
+
+- the shared information space in which the interaction takes place;
+- the functional role of the major participants;
+- the required supporting information resources;
+- the type and configuration of the various interactions; and
+- the need to interface associated application processes.
+
+While there is no standard symbology for constructing the functional model, care should be taken to select a form of presentation that reflects the essential functional elements of the application in a clear and concise way.
+
+## 4.4 Application matrix
+
+An application matrix maps user requirements onto technical functionalities. The principles for developing attribute tables are the following:
+
+- 1) Application matrices are intended to facilitate the mapping of user needs with technical functionalities in an easily understandable form.
+- 2) Application matrices enable the evaluation of service functionalities in a systematic and compact form.
+- 3) Application matrices facilitate assessing the importance of functionalities in regard to user needs.
+
+Table 1 shows as an example a part of an application matrix:
+
+**Table 1/F.701 – Application matrix template**
+
+| User needs                   | Technical functionalities                  |                       |                         |
+|------------------------------|--------------------------------------------|-----------------------|-------------------------|
+|                              | Differential delay between audio and video | Image repetition rate | Image resolution        |
+| Lip reading (with head view) | < 100 ms                                   | > 20 pictures/s       | QCIF (178 × 144 pixels) |
+| Sign language                | –                                          | > 20 pictures/s       | CIF (358 × 288 pixels)  |
+
+The following are examples of user needs:
+
+- discussion of a jointly viewed document;
+- the need to move around;
+- the need to scrutinize fine details of a presented object.
+
+The following are examples of functionalities the applications may require:
+
+- shared viewing space for images;
+- cordless communication access;
+- high resolution image transfer.
+
+The development of the matrix requires further study.
+
+## 4.5 Summary
+
+A script may include a prose description, an application scenario, implementation notes and an application matrix. (or several matrices for different environments or different times in the communication). Some scripts may contain only part of those elements.
+
+# 5 Harmonization of Application Scripts with other bodies
+
+Application scripts can be developed by the ITU or by other standards organizations, industry fora, consortia, user groups or individual end users. An application script, before being used as the basis for launching a new service development or evaluation effort by the ITU-T, should be discussed with the end user community if possible or reasonable. This discussion should take place between the relevant study groups and those organizations that have been identified as most representative of relevant end user interests, in accordance with ITU-T policies and procedures (see ITU-T Recommendation A.4).
+
+# APPENDIX I
+
+## Definitions
+
+Definitions taken from ITU-T Recommendation F.700.
+
+**I.1 application:** An Application is a set of activities performed to respond to the needs of the users in a given situation for purposes such as business, education, personal communication or entertainment. It implies software and hardware utilization, could be performed in a fully or partially automatic way and could be accessed locally or remotely. In the last case, it requests use of telecommunication services.
+
+**I.2 multimedia {MHEG}:** The term multimedia is an adjective which means relative to two or more media; it must be attached to a noun which provides the context. For example, multimedia service or application, multimedia terminal, multimedia network and multimedia presentation.
+
+**I.3 multimedia application:** A Multimedia Application is an application that requests the handling of two or more representation media (information types) simultaneously, which constitute a common information space. Examples are cooperative document editing, long distance meetings, remote surveillance, medical document remote analysis and teletraining.
+
+**I.4 multimedia service:** Multimedia services are telecommunication services that handle two or more types of media in a synchronized way from the user's point of view. A multimedia service may involve multiple parties, multiple connections, and the addition or deletion of resources and users within a single communication session.
+
+# APPENDIX II
+
+## Multimedia medical consultation
+
+## II.1 Prose Description
+
+Medical consultation involves interactive multimedia communications between medical experts located at two or more separate locations. This communication is generally initiated by a doctor desiring to discuss a particular patient's case with subject matter experts and may occur between the doctor and one consultant only, or may require an interactive conference arrangement between the doctor and several consultants simultaneously.
+
+In the course of the consultation, information may also be required from remote databases containing the patient's medical files; from one or more diagnostic test centres in the form of X-rays, sonograms, electrocardiographs or similar medical images; or from a reference library containing technical information, illustrative medical images, or other supporting material required to facilitate the consultation. This material may be textual, aural, graphical or imagery in nature and may be stored in a multimedia format.
+
+Participants in the consultation may be located in an office or medical facility having access to the full range of broadband multimedia telecommunications capabilities; or located in a moving vehicle, on a golf course, or at some other remote location having limited communications access. In order to accommodate all eventualities, provisions for dynamic resource arbitration and allocation, both during "call" initiation and while the "call" is in progress, are required to ensure that the more important aspects of the interaction are fully satisfied.
+
+## II.2 Application Scenario
+
+This scenario is provided in two parts to better represent the wide range of communication environments within which a multimedia medical consultation could take place.
+
+### II.2.1 Full multimedia support capability
+
+Dr. "X" is a world recognized authority on bone structure and is widely consulted by other doctors on a frequent basis. Usually, this consultation takes place in Dr. "X"'s office where he has a state-of-the-art multimedia communications terminal with a large high definition video display. A typical consultation might proceed in the following manner:
+
+Stage 1 – Dr. "X" is called by Dr. "Y" via videophone requesting consultation regarding a patient suffering from multiple fractures of the upper foot resulting from an automobile accident. After briefly covering the nature of the injury, Dr. "Y" transmits the patient's examination chart. The full screen video image on Dr. "X"'s screen immediately changes to a two-partition representation depicting the patient's chart in the left half and a reduced video image of Dr. "Y" in the right half.
+
+Stage 2 – Dr. "Y" is on duty in the emergency room of a local hospital and, after discussing the general aspects of the case with Dr. "X" in a face-to-face videophone presentation, switches to his handheld remote videophone camera in order to provide Dr. "X" with a visual survey of the damaged foot.
+
+Stage 3 – With the visual inspection completed, Dr. "X" requests transmission of the X-rays depicting the damaged area taken from different orientations. The two-partition screen presentation is quickly divided into four partitions, one for each of the X-rays to be transmitted.
+
+Stage 4 – After careful scrutiny, Dr. "X" selects the partition which gives the best view of the upper ankle area where most of the serious damage appears to have occurred. The partitioned screen is quickly replaced with a full screen, high resolution depiction of the selected image, enabling Dr. "X" to make a more detailed inspection of the area of interest.
+
+Stage 5 – Careful examination of the tarsal bone structure indicates considerable damage to the tibialis posterior tendon and associated muscle area, a complicating factor which requires the assistance of a third specialist. With the consent of Dr. "Y", Dr. "X" initiates a videoconference call to Dr. "Z", a specialist in tendon reconstruction.
+
+Stage 6 – After advising Dr. "Z" of the nature of the emergency, the three doctors continue discussion of the case. As the videoconference progresses, the patient's examination chart, medical files, X-rays and other reference information are brought into the conference as required, either through the transmission of additional data or recovered from local "memory" if previously transmitted.
+
+Stage 7 – At the end of the conference, Dr. "Y" thanks Drs. "X" and "Z" for their assistance and terminates the consultation.
+
+### II.2.2 Restricted multimedia support capability
+
+A week later, another emergency occurs, this time involving a patient whose foot has been crushed in a logging accident. Dr. "Y" again calls Dr. "X" for consultation. While Dr. "X" is available for consultation, it is his day off and all calls are automatically routed either to his home terminal or his portable terminal, depending upon the doctor's location at any particular point in time. In this case, Dr. "X" happens to be on the golf course, accessible from the portable terminal in his golf cart.
+
+In general, the consultation proceeds in a manner similar to that of the previous week. However, due to size limitations placed on the portable terminal and the reduced bandwidth available through the mobile network, service expectations are modified and focused on the more important aspects of the interaction. The less important features are relegated to a nice-to-have but non-essential category. With this in mind, the consultation proceeds in the following manner:
+
+Stage 1 – Dr "Y" initiates a videophone call to Dr "X" to request consultation. Since Dr. "X" is now using his portable terminal, he has elected to receive calls in the "voice only" mode. The network, complying with this service request, establishes the initial connection for voice communication only.
+
+Stage 2 – After advising Dr. "X" of the circumstances surrounding the emergency, Dr. "Y" asks Dr. "X" to switch his terminal to videophone operation in order to visually survey the area of injury. Dr. "Y", recognizing that Dr. "X" is communicating from a portable terminal, bypasses the normal full field view camera on his videophone terminal and activates the handheld remote scanner, holding the camera steady in the vicinity of the injury to compensate for the reduced "motion" response characteristics of Dr. "X"'s portable terminal.
+
+Stage 3 – With visual inspection completed, Dr. "X" requests transmission of an X-ray for the orientation he feels will best portray the extent of damage. To compensate for the size of the portable video display and the reduced transmission rate, Dr. "X" has purchased an enhanced storage feature for his basic portable multimedia terminal in order to capture the considerable amount of data required for high resolution X-rays. In addition, he is willing to accept longer transmission delay in order to obtain the necessary image resolution.
+
+Stage 4 – After careful scrutiny of the damaged area, Dr. "X" requests transmission of an additional X-ray which he hopes will depict the damaged area to better advantage. He elects not to choose a split screen presentation due to the small size of the portable video display, but to take advantage of the local data storage and image manipulation features, which allow him to zoom in on areas of particular interest and to change from one locally stored image to the other at near "office" response times.
+
+Stage 5 – Careful examination of the injury again indicates the need for additional consultation with Dr. "Z" regarding the extensive damage which has occurred to the tendons in the vicinity of the ankle. With the consent of Dr. "Y", Dr. "X" places a voice only conference call to Dr. "Z".
+
+Stage 6 – After advising Dr. "Z" of the nature of the emergency and that he is calling from a mobile terminal, Dr. "X" asks Dr. "Y" to initiate a three-way videoconference to further discuss the case. In order to make maximum use of the bandwidth available for the more important imagery data, Dr. "X" elects to join the videoconference in the AUDIOGRAPHICS-only mode (audio plus still image and graphics). As the videoconference progresses, X-ray and other visual information is brought into the conference as required, either through the transmission of additional data or recovered from local memory if the information had been previously sent.
+
+Stage 7 – At the end of the teleconference, Dr. "Y" again thanks both Drs. "X" and "Z" for their assistance and terminates the consultation.
+
+## **II.3 Implementation notes**
+
+### **II.3.1 Related applications**
+
+This Application is closely related to REMOTE MEDICAL DIAGNOSTICS, but differs with respect to the time urgency of the interaction, the terminal facilities and transmission resources available, and the principal media of information interchange.
+
+### **II.3.2 Associated applications**
+
+AUTOMATED ACCOUNTING AND BILLING for the consultants' time, and a permanent record of the interaction (AUTOMATIC ARCHIVAL) are desirable adjuncts to this application.
+
+### **II.3.3 Security/privacy**
+
+The communications associated with this application are privileged in nature and require access to databases containing confidential information protected by privacy laws in most locations.
+
+### **II.3.4 Service flexibility**
+
+There is a need for automated service mechanisms which will allow for:
+
+- 1) initial "call" establishment at the highest common denominator of service capabilities shared by all participants; and
+- 2) the dynamic and selective modification of service parameters during "call" progress.
+
+#### **II.3.5 Performance trade-offs**
+
+The primary media components are VOICE and IMAGERY. Resolution requirements for the medical images take precedence over the associated increase in transmission delay. For portable terminal applications, resolution also takes precedence over the area of spatial coverage as long as mechanisms are provided for selecting the boundaries of the area to be viewed.
+
+The consultation may be conducted in either a full-motion video or still-frame audiographic mode of operation, depending upon the terminal and transmission capabilities available to the participants.
+
+
+
+# **SERIES OF ITU-T RECOMMENDATIONS**
+
+|                 |                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                              |
+| Series B        | Means of expression: definitions, symbols, classification                                                                      |
+| Series C        | General telecommunication statistics                                                                                           |
+| Series D        | General tariff principles                                                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                              |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                |
+| Series G        | Transmission systems and media, digital systems and networks                                                                   |
+| Series H        | Audiovisual and multimedia systems                                                                                             |
+| Series I        | Integrated services digital network                                                                                            |
+| Series J        | Transmission of television, sound programme and other multimedia signals                                                       |
+| Series K        | Protection against interference                                                                                                |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant                                        |
+| Series M        | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                |
+| Series O        | Specifications of measuring equipment                                                                                          |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                   |
+| Series Q        | Switching and signalling                                                                                                       |
+| Series R        | Telegraph transmission                                                                                                         |
+| Series S        | Telegraph services terminal equipment                                                                                          |
+| Series T        | Terminals for telematic services                                                                                               |
+| Series U        | Telegraph switching                                                                                                            |
+| Series V        | Data communication over the telephone network                                                                                  |
+| Series X        | Data networks and open system communications                                                                                   |
+| Series Y        | Global information infrastructure and Internet protocol aspects                                                                |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                           |

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+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' written across the center.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**F.71**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# **OPERATIONS AND QUALITY OF SERVICE TELEGRAPH SERVICES** ---
+
+# **INTERCONNECTION OF PRIVATE TELEPRINTER NETWORKS WITH THE TELEX NETWORK**
+
+**ITU-T Recommendation F.71**
+
+(Extract from the *Blue Book*)
+
+---
+
+## NOTES
+
+1 ITU-T Recommendation F.71 was published in Fascicle II.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## **INTERCONNECTION OF PRIVATE TELEPRINTER NETWORKS WITH THE TELEX NETWORK**
+
+The CCITT,
+
+*considering*
+
+- (a) the operational provisions for the international telex service laid down in Recommendation F.60;
+- (b) that in various countries possessing public telex networks there also exist numerous private teleprinter networks using their own exchanges and conforming with the national regulations of the country concerned;
+- (c) that the owners of these private networks are frequently substantial users of the telex service employing multiple subscriber lines;
+- (d) that, consequently, it is very desirable to allow the through-connection of calls between teleprinters connected to private exchanges and those connected to the public telex network;
+- (e) that in the telephone service the ability to establish calls between stations connected to private and public exchanges has long been available;
+- (f) that the operation of the international public telex service must be neither hampered nor limited by private exchanges and hence the conditions for interconnection of the two types of network should be standardized,
+
+*declares the following*
+
+- 1 Any terminal in a private network that may be directly connected (circuit switched) to a terminal in the international telex network must conform to the relevant requirements for terminals in the telex network as laid down in the Series F and S Recommendations.
+- 2 A private network must not be allowed to provide communication between two external telex stations. For the provisions concerning interconnection between international leased circuits and the telex network, see Recommendation D.1 [1].
+- 3 Where a private network uses a message store-and-forward system, it may be authorized to accept and deliver messages from and to the public network. The signals from the private network must always conform with the telex network's signalling standards.
+- 4 When a private network connected to the telex network offers an external caller the facility of selecting a given extension directly, this should be clearly indicated in the public telex directory.
+- 5 Either two-stage or single stage selection may be used as a means of automatic selection of a subsidiary station in the private network by an external caller.
+- 6 For two-stage selection the following provisions should be applied:
+  - 1) The first stage of the selection should designate the called private network, using a conventional national subscriber number. Following the normal telex procedure, this sequence should start the selection process, resulting in the caller's being connected to a teleprinter (or any other appropriate device in the private network) that is ready to record a message. For networks where the called telex subscriber's answer-back is tripped automatically, this answer-back code must designate and be common to the whole of the private network concerned.
+  - 2) Application of the second stage by the calling telex subscriber is optional. The selection sequence used to designate a particular extension station may have a special composition for the network that is quite independent of the national telex numbering scheme, but it must always consist of teleprinter characters.
+
+- 3) If the caller wishes to use the second stage of selection, he advises the private network by sending the sequence **XVXV** (combination 24, 22, 24 and 22 successively), to which the network responds with a proceed-to-select signal  $\leftarrow \equiv \downarrow \text{GA} \rightarrow$  (combinations 27, 28, 29, 7, 1 and 31 successively).
+- 4) This optional second stage of selection is ignored by the telex network. The corresponding selection time in the private network is charged in the same way as a telex call. The composition of the answer-back codes transmitted, where appropriate, after the second stage of selection may therefore be left to the discretion of the subscriber.
+
+7 Where single-stage selection is used for connection to extension stations, the following provisions should be applied.
+
+- 1) The single sequence used to select an extension station must be in the form of a national subscriber number, comprising a number to designate the called private network followed by further digits to specify the particular station required. When the caller sends this full sequence of digits, through-connection to the required extension is achieved, first by selection in the public network then in the private network. For networks where the called telex subscriber's answer-back is automatically tripped, the answer-back sent when the complete connection has been set up is specific to the selected extension.
+- 2) If the caller wishes to communicate, not with any specific subsidiary extension, but with a teleprinter (or any other appropriate device in the private network) that is ready to record a message, the selection sequence should consist of the number designating the private network followed by the figure **0**.
+- 3) If the caller only sends a selection sequence specifying the private network (i.e. neither **0**, nor a specific extension number nor an end-of-selection signal is added), the call should be automatically diverted after a period of 10 s to a main station.
+- 4) If the caller specifies a particular extension station that is engaged or otherwise unavailable, the call should be automatically diverted to a main station.
+- 5) With single-stage selection, the answer-back codes for all stations, including extension stations, must comply with the requirements in Recommendation F.60 for the composition of telex answer-back codes.
+
+8 In the event that the external caller fails either partially or totally to meet the requirements of the procedures of a private teleprinter network as in §§ 3 to 7 above, the call should be intercepted by, or directed to, an enquiry teleprinter (or any other appropriate device) in the private network. On no account must the call be terminated by the private network if the procedures are not followed.
+
+## Reference
+
+- [1] CCITT Recommendation *General principles for the lease of international (continental and intercontinental) private leased telecommunication circuits*, Rec. D.1.

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+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.72**
+
+(10/96)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Telegraph service – The international telex service
+
+---
+
+**The international telex service – General  
+principles and operational aspects of a store  
+and forward facility**
+
+ITU-T Recommendation F.72
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T F-SERIES RECOMMENDATIONS NON-TELEPHONE TELECOMMUNICATION SERVICES
+
+|                                                                 |                  |
+|-----------------------------------------------------------------|------------------|
+| TELEGRAPH SERVICE                                               | F.1–F.109        |
+| Operating methods for the international public telegram service | F.1–F.19         |
+| The gentex network                                              | F.20–F.29        |
+| Message switching                                               | F.30–F.39        |
+| The international telemessage service                           | F.40–F.58        |
+| <b>The international telex service</b>                          | <b>F.59–F.89</b> |
+| Statistics and publications on international telegraph services | F.90–F.99        |
+| Scheduled and leased communication services                     | F.100–F.104      |
+| Phototelegraph service                                          | F.105–F.109      |
+| MOBILE SERVICE                                                  | F.110–F.159      |
+| Mobile services and multdestination satellite services          | F.110–F.159      |
+| TELEMATIC SERVICES                                              | F.160–F.399      |
+| Public facsimile service                                        | F.160–F.199      |
+| Teletex service                                                 | F.200–F.299      |
+| Videotex service                                                | F.300–F.349      |
+| General provisions for telematic services                       | F.350–F.399      |
+| MESSAGE HANDLING SERVICES                                       | F.400–F.499      |
+| DIRECTORY SERVICES                                              | F.500–F.549      |
+| DOCUMENT COMMUNICATION                                          | F.550–F.599      |
+| Document communication                                          | F.550–F.579      |
+| Programming communication interfaces                            | F.580–F.599      |
+| DATA TRANSMISSION SERVICES                                      | F.600–F.699      |
+| AUDIOVISUAL SERVICES                                            | F.700–F.799      |
+| ISDN SERVICES                                                   | F.800–F.849      |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850–F.899      |
+| HUMAN FACTORS                                                   | F.900–F.999      |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+## FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation F.72 was revised by ITU-T Study Group 1 (1993-1996) and was approved by the WTSC (Geneva, 9-18 October 1996).
+
+---
+
+## NOTE
+
+In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+© ITU 1997
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU.
+
+## CONTENTS
+
+|      |                                                           | <i>Page</i> |
+|------|-----------------------------------------------------------|-------------|
+| 1    | Scope.....                                                | 1           |
+| 2    | General .....                                             | 1           |
+| 3    | Service requirements .....                                | 3           |
+| 3.1  | Message identification .....                              | 3           |
+| 3.2  | Service signals .....                                     | 3           |
+| 3.3  | Duration of message storage .....                         | 3           |
+| 3.4  | Maximum message length and duration .....                 | 3           |
+| 3.5  | Store full indication .....                               | 4           |
+| 3.6  | End of transaction and end of message signal .....        | 4           |
+| 3.7  | Input transaction accepted .....                          | 5           |
+| 3.8  | Message security .....                                    | 5           |
+| 3.9  | Advice of non-delivery/delivery .....                     | 5           |
+| 3.10 | Call records .....                                        | 5           |
+| 3.11 | Incomplete message .....                                  | 6           |
+| 4    | Facilities .....                                          | 6           |
+| 4.1  | Single address .....                                      | 6           |
+| 4.2  | Multi-address .....                                       | 6           |
+| 4.3  | Follow-on messages .....                                  | 6           |
+| 4.4  | Classes of delivery .....                                 | 6           |
+| 4.5  | Cancellation .....                                        | 6           |
+| 4.6  | Address correction .....                                  | 6           |
+| 5    | Quality of Service .....                                  | 7           |
+| 5.1  | Loss probability in the store and forward procedure ..... | 7           |
+| 5.2  | Error protection .....                                    | 7           |
+| 5.3  | Duration of service .....                                 | 7           |
+| 5.4  | Number of circuits .....                                  | 7           |
+| 5.5  | Minimum storage capacity .....                            | 7           |
+| 6    | Access principles .....                                   | 7           |
+| 7    | Access procedures .....                                   | 7           |
+| 7.1  | General .....                                             | 7           |
+| 7.2  | Access from a telex subscriber .....                      | 8           |
+| 7.3  | Service request .....                                     | 8           |
+| 7.4  | Message input .....                                       | 8           |
+| 8    | Contents of the address line .....                        | 8           |
+| 8.1  | Address line .....                                        | 8           |
+| 9    | Abnormal conditions during message input .....            | 10          |
+| 10   | Message status enquiry .....                              | 10          |
+| 10.1 | General procedures .....                                  | 10          |
+| 10.2 | Status enquiry information field content .....            | 10          |
+| 10.3 | The status report .....                                   | 10          |
+| 10.4 | Status report field content .....                         | 10          |
+| 11   | Delivery procedure .....                                  | 11          |
+| 11.7 | Procedures for delivery of messages .....                 | 11          |
+| 12   | Notification procedures .....                             | 14          |
+| 12.1 | Types of notification .....                               | 14          |
+| 12.2 | Notification delivery procedures .....                    | 14          |
+
+|                                                                    | <i>Page</i> |
+|--------------------------------------------------------------------|-------------|
+| 13    Delivery retry procedures.....                               | 14          |
+| 13.3    Recorded message from the called subscriber .....          | 14          |
+| 14    Contents of delivery/non-delivery notifications .....        | 14          |
+| 15    Internationally interconnected store and forward units ..... | 14          |
+
+
+
+# **THE INTERNATIONAL TELEX SERVICE – GENERAL PRINCIPLES AND OPERATIONAL ASPECTS OF A STORE AND FORWARD FACILITY**
+
+*(Melbourne, 1988; revised Helsinki, 1993 and Geneva, 1996)*
+
+The ITU-T
+
+*considering*
+
+- (a) that telex store and forward is included in Recommendation F.63 as an additional facility within the international telex service;
+- (b) that telex store and forward facilities have been and are being introduced by many countries;
+- (c) that a requirement for access via the international telex service from an originator in one country to a telex store and forward facility in another country has been identified;
+- (d) that a store and forward facility in one country may be interconnected with the store and forward facility in another country via Message Handling Services in accordance with F- and X-Series Recommendations,
+
+*unanimously declares*
+
+that the general principles and operational aspects described in this Recommendation should be adopted for the provision of store and forward as an additional facility within the international telex service.
+
+## **1 Scope**
+
+1.1 This Recommendation is one of a series which define telex store and forward facilities. The other Recommendations are:
+
+- Recommendation U.80 – International telex store and forward – Access from a telex subscriber.
+- Recommendation U.81 – International telex store and forward – Delivery to a telex subscriber.
+
+1.2 The service requirements and Quality of Service provisions along with the single address facility and classes of delivery specified in this Recommendation are essential for the store and forward facility. The other facilities are optional and will be provided at the discretion of the Administration operating the Store and Forward Unit (SFU).
+
+## **2 General**
+
+2.1 Within the store and forward facility, communication between terminals is on a store and forward basis via the SFU, thus conversational mode connection between terminals is not provided.
+
+2.2 The following two types of configuration have been identified as shown in Figure 1:
+
+- a) *International store and forward* is where a subscriber in Country A accesses the store and forward unit in Country B for the transmission of messages to that country.
+- b) *Interconnected store and forward* is where the store and forward unit in Country A is connected to the store and forward unit in Country B for the transmission of messages between the two countries.
+
+![Diagram a) Case of international store and forward. It shows a flow from a Telex originator in Country A, through a Telex network, to an SFU in Country B, and finally to an Addressee in Country B. A 'Message deposit' is indicated at the international boundary.](3121ebddccf183ca63bb9781be440a7e_img.jpg)
+
+The diagram illustrates the flow of a message in an international store and forward scenario. On the left, in Country A, a 'Telex originator' sends a message to a 'Telex network'. A horizontal line labeled 'Message deposit' crosses the 'International boundary' and points to a circle labeled 'SFU' in Country B. From the 'SFU', an arrow labeled 'Message delivery' points to the 'Addressee' in Country B. The 'Telex network' in Country B is also connected to the 'Addressee'.
+
+Diagram a) Case of international store and forward. It shows a flow from a Telex originator in Country A, through a Telex network, to an SFU in Country B, and finally to an Addressee in Country B. A 'Message deposit' is indicated at the international boundary.
+
+a) Case of international store and forward
+
+![Diagram b) Case of interconnected store and forward. It shows a flow from a Telex originator in Country A, through a Telex network, to an SFU, then to a central 'Message handling services' block across the international boundary, then to another SFU, and finally to an Addressee in Country B. A 'Message transfer' is indicated between the two SFUs.](990567efebf979be51f56d1150012c9d_img.jpg)
+
+The diagram illustrates the flow of a message in an interconnected store and forward scenario. On the left, in Country A, a 'Telex originator' sends a message to a 'Telex network', which then connects to an 'SFU'. A 'Message deposit' arrow points to this 'SFU'. From the 'SFU', the message goes to a 'Message handling services' block. A double-headed arrow labeled 'Message transfer' spans across the 'International boundary' between the 'Message handling services' in Country A and another 'SFU' in Country B. From this 'SFU', a 'Message delivery' arrow points to the 'Addressee' in Country B. The 'Telex network' in Country B is also connected to the 'Addressee'.
+
+Diagram b) Case of interconnected store and forward. It shows a flow from a Telex originator in Country A, through a Telex network, to an SFU, then to a central 'Message handling services' block across the international boundary, then to another SFU, and finally to an Addressee in Country B. A 'Message transfer' is indicated between the two SFUs.
+
+b) Case of interconnected store and forward
+
+Figure 1/F.72 – General model for the deployment of SFUs
+
+2.3 Whilst the Recommendation addresses international and interconnected store and forward, the delivery procedures can be used for international traffic from a national SFU.
+
+### 2.4 Limitations of access to a store and forward facility
+
+2.4.1 The configurations identified in 2.2 will be provided on the basis of bilateral agreements between the Administrations concerned.
+
+2.4.2 An Administration operating an SFU should be responsible for the barring of international access from unauthorized users and for barring unauthorized types of call such as transit calls to specific countries. The method of barring shall be the responsibility of the Administration operating the SFU and is beyond the scope of this Recommendation.
+
+2.4.3 It may also be necessary for Administrations to make provision to selectively block access to SFUs in other countries.
+
+## **3 Service requirements**
+
+### **3.1 Message identification**
+
+The SFU will provide to the subscriber a unique message reference readily identifiable for every message, comprising:
+
+- a) the date and time of message input as provided to the originating telex subscriber in accordance with Recommendation U.80; and
+- b) the message reference number as allocated and provided to the originating telex subscriber at the time of input of the message.
+
+### **3.2 Service signals**
+
+#### **3.2.1 Service signals received by the SFU**
+
+All standardized telex service signals (see Recommendation F.60 for a list of code expressions and appropriate U-Series Recommendations for their format) must be recognized by the SFU. The retry procedure will be according to the principles of Recommendation U.40. It is desirable that the SFU attempt to interpret non-standard service signal and continue with the appropriate procedure. If the SFU is unable to interpret a non-standard service signal, the SFU should give a non-delivery notification to the calling subscriber and repeat the service signal in the format received.
+
+#### **3.2.2 Code expressions sent by the SFU**
+
+The following code expressions may be generated by the SFU:
+
+- |     |                                                                                        |
+|-----|----------------------------------------------------------------------------------------|
+| ADD | Please input your international telex number                                           |
+| BMC | No end of message or end of transmission received, therefore message cancelled         |
+| IAB | Invalid answerback from destination (only sent as part of a non-delivery notification) |
+| IMA | Input message acknowledgement                                                          |
+| ITD | Input transaction accepted for delivery                                                |
+| ITR | Input transactions rejected                                                            |
+| LDE | Maximum acceptable message length or duration has been exceeded                        |
+| OCC | Store full, SFU unavailable                                                            |
+| REJ | Address rejected                                                                       |
+| TMA | Maximum number of addresses exceeded                                                   |
+
+### **3.3 Duration of message storage**
+
+The retry procedure applied by the SFU should be in accordance with the principles of Recommendation U.40. However, the period for which the SFU should retain responsibility for the message should not exceed 24 hours from time of input. If delivery has not been effected, the procedure as in 3.9 should apply.
+
+### **3.4 Maximum message length and duration**
+
+**3.4.1** All SFUs should have sufficient capacity to accept at least 24 000 characters per single message. Exceptionally, some SFUs may set this limit at 12 000 characters or even lower. Subscribers should therefore be advised by their Administrations as to the maximum message length accepted by those SFUs to which they have access.
+
+**3.4.2** In the case of interconnected SFUs, the maximum acceptable message length of the SFUs should be agreed to by the Administrations operating the SFUs.
+
+**3.4.3** The maximum input duration for a single transaction should be two hours.
+
+**3.4.4** If the maximum acceptable message length or duration is reached, the sender should be advised by sending to him the service code LDE. Prior to sending the service code LDE, an attempt should be made to stop his transmission by sending the letter T, repeatedly in accordance with Recommendation S.4.
+
+**3.4.5** After sending the service code LDE, the SFU will wait for the End of Message signal (EOM) or End of Transaction signal (EOT) and proceed in accordance with 3.6.
+
+### **3.5 Store full indication**
+
+Messages should cease to be accepted when the level of store capacity is reduced to a predetermined state to ensure that any messages in the process of being transmitted to the unit can be accepted in their entirety, bearing in mind the provisions of 3.4. The unit will return the service code OCC in response to attempts to access the unit for message input.
+
+### **3.6 End of transaction and end of message signal**
+
+**3.6.1** At the end of each transaction, an End of Transaction (EOT) signal is required. This signal is +++. However, for follow-on messages, an End of Message (EOM) signal is required at the end of each individual message. The functions of these signals are described in Table 1.
+
+**Table 1/F.72 – Functions of end of message and end of transaction signals**
+
+| <b>Sequence</b> | <b>Mnemonic</b> | <b>Function</b>                                                                                                                                                                                              | <b>Action by SFU</b>                                                                                                                                                                            |
+|-----------------|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| NNNN            | EOM             | Used to separate different messages (end of message) deposited in the SFU during the same transaction for delivery to different addresses or groups of addresses.                                            | 1) Enables follow-on calls to be provided by the SFU.<br>2) Will result in force clearing by the SFU and cancellation of the message(s) if not followed by either an address or the EOT signal. |
+| NNNNACK         | EOM(ACK)        | Used to request Input Message Acknowledgement (IMA) of previously deposited messages, to separate messages, and to request a follow-on call.                                                                 | As for EOM, except that messages already acknowledged will be delivered whatever the subsequent action by either the subscriber or the SFU.                                                     |
+| +++             | EOT             | End of transaction signal, used to indicate to the SFU that the transaction has been completed and also to request message reference information for previously submitted messages not already acknowledged. | Provides message reference information and initiates clearing.                                                                                                                                  |
+
+**3.6.2** If there is a stop in transmission for 30 seconds without receipt of either an EOM or EOT signal, the code expression GA should be sent to the subscriber.
+
+**3.6.3** If the EOM/EOT signal is not received, or transmission does not resume within a further 30 seconds, the SFU shall initiate the clear down procedure.
+
+**3.6.4** The incomplete message should either be cancelled or, optionally, sent to an operator assistance position.
+
+**3.6.5** If the message is to be cancelled before clearing the connection, the SFU should inform the subscriber that no EOM/EOT signal has been received by sending the code expression BMC.
+
+**3.6.6** In the event of clear down by the caller without an EOM or EOT signal, the incomplete message(s) will be processed as in 3.6.4.
+
+### **3.7 Input transaction accepted**
+
+On receipt of an EOT signal, the SFU should send an input transaction accepted for delivery signal (ITD) notifying the subscriber that the message(s) has/have been accepted and that delivery will be attempted. Delivery should be attempted even if the call is cleared before the ITD is sent. The ITD should be followed by the message reference(s) and, if applicable, number of messages.
+
+### **3.8 Message security**
+
+#### **3.8.1 Message acceptance**
+
+**3.8.1.1** The SFU should only accept messages for delivery to destination addresses served by that SFU. Any messages for other destinations should be refused with code expression NA for the reason of non-delivery.
+
+**3.8.1.2** The SFU should not accept message input unless acceptable identification of the originating subscriber has been received at call set-up in accordance with Recommendations U.74 and U.80.
+
+**3.8.1.3** The SFU may validate the called address(es). If this validation is unsuccessful for all addresses, the message should be rejected and the code expression ITR should be returned (see Recommendation U.80). However, positive validation result does not guarantee that the message can be delivered to the given address.
+
+#### **3.8.2 Expected answerback comparison**
+
+Subscribers may provide all or part of the expected answerback to enable the SFU to validate the answerback received in order to enhance message security. This information should be compared with the answerback received by the SFU at call set-up to the destination subscriber and, if found not to be in compliance, the message should not be delivered.
+
+A non-delivery notification should be given to the originating subscriber including the code expression IAB and optionally repeating the destination answerback actually received. The method used for checking the answerback is the responsibility of the Administration operating the SFU. If the subscriber does not provide the expected answerback, the SFU may provide validation by comparing the called party's national telex number with the received answerback.
+
+### **3.9 Advice of non-delivery/delivery**
+
+**3.9.1** Automatic advice of non-delivery should be given to the subscriber as soon as the delivery retry procedure in accordance with Recommendation U.40 has been terminated. In the case of multi-address messages, advice of non-delivery may be issued on a per message or per address basis, the former being preferred when the retry procedure has been completed for all of the specified addresses. If an advice of non-delivery cannot be delivered, it should be sent to a manual assistance position associated with the SFU. Normal telex operator calling procedures must be observed when attempting manually-assisted advice of non-delivery.
+
+**3.9.2** Automatic advice of delivery is preferred. However, it will be provided at the discretion of the Administrations operating the SFU service.
+
+**3.9.3** In the case of interconnected store and forward, the destination SFU should pass all delivery, non-delivery and status information to the originating SFU from which advice will be sent to the originating subscriber.
+
+**3.9.4** The provision of a periodic (e.g. daily) notification or journal may be considered as an adequate form of delivery, non-delivery and status information.
+
+**3.9.5** Notification of message delivery/non-delivery may be on a per message or per address basis. This Recommendation assumes that notification will be returned, as a minimum, on a per message basis.
+
+### **3.10 Call records**
+
+Records of effective and ineffective calls should be maintained and forwarded to the origin Administration at regular intervals (at least once per month) for general accounting, billing, and statistical purposes. The Administrations should agree bilaterally on the format and method of information transfer.
+
+### 3.11 Incomplete message
+
+In the case of partial delivery of a message by the SFU, the header "Possible duplicate message" should be appended to the message at subsequent delivery.
+
+## 4 Facilities
+
+### 4.1 Single address
+
+This is where a message is sent via an SFU to another telex subscriber addressee and is a minimum requirement. In addition, messages may also be sent to subscribers of other services (e.g. Teletex, Videotex) in accordance with Recommendation U.80.
+
+### 4.2 Multi-address
+
+4.2.1 A multi-address message is where a common text is sent to two or more addresses. This facility should be provided only for addresses in the same country as the destination SFU and requires bilateral agreement.
+
+4.2.2 The acceptable number of individual addresses for any one message will be decided by the Administrations operating the SFU but should be at least 20.
+
+4.2.3 If the maximum acceptable number of addresses is exceeded, the SFU shall clear the communication after sending the code expression TMA.
+
+### 4.3 Follow-on messages
+
+This facility enables the subscriber to enter more than one message into storage without clearing, each message being preceded by a different header, and is considered to be highly desirable. At the completion of the transaction, the unit should advise the sender of the number of messages received. Each separate message must have a unique reference number. See also 3.6.1.
+
+### 4.4 Classes of delivery
+
+The following three classes of delivery have been identified; one or more of these should be offered by Administrations:
+
+- a) *Normal delivery* – The SFU attempts to deliver the message as soon as operationally feasible after receipt.
+- b) *Deferred delivery* – The delay can be either:
+  - i) set by the Administration offering the SFU facility;
+  - ii) set by the calling subscriber, such that the delivery of the message is not attempted until after the expiration of the indicated delay.
+- c) *Time limited delivery* – Where the SFU attempts to deliver the message as soon as operationally feasible up to a customer – specified time limit not exceeding 24 hours.
+
+These classes of delivery should be offered on a per address basis.
+
+### 4.5 Cancellation
+
+The facility whereby the originating subscriber may cancel a message after it has been accepted by the SFU is not permitted.
+
+### 4.6 Address correction
+
+When provided, the facility whereby the originating subscriber can correct an address during input should be implemented in accordance with Recommendation U.80.
+
+## **5 Quality of Service**
+
+### **5.1 Loss probability in the store and forward procedure**
+
+**5.1.1** The introduction of an SFU into the international telex network should not increase, on a per address basis, the probability of message loss or corruption.
+
+**5.1.2** In international store and forward, the unique identification of each message should enable the system to provide information as to the status of any message upon interrogation.
+
+**5.1.3** In the event of system failure, all accepted messages should be traceable. However, if messages have to be cancelled, the originating subscriber should be informed.
+
+### **5.2 Error protection**
+
+The overall error protection should be in accordance with Recommendation F.10 and the error rate should therefore not be greater than 3 in 100 000.
+
+### **5.3 Duration of service**
+
+The automatic service should be continuous.
+
+### **5.4 Number of circuits**
+
+Where international store and forward exists, the amount of traffic generated and received by the SFU should be considered when determining the number of international circuits in conformity with Recommendation F.64. However, the actual number of circuits will depend on the capacity of the SFU. Care must be taken that routes are not congested by the SFU. Such factors as the time difference between the countries concerned need to be taken into account.
+
+### **5.5 Minimum storage capacity**
+
+The storage capacity will vary from unit to unit according to the volume of traffic. However, it should be sufficient to provide a grade of service not less than that of the international telex service provided by that Administration.
+
+## **6 Access principles**
+
+**6.1** The procedure defined in this clause is a two-stage selection procedure whereby the calling telex subscriber gains access to a foreign SFU in the first stage of selection and either inputs the called address(es) and message, or requests a status report, in the second stage of selection, after the return of a call-connect by the called SFU.
+
+**6.2** Message input from both manual and automatic emitting devices should be accommodated.
+
+**6.3** The telex address of the originating telex subscriber should be determined in accordance with Recommendation U.74. It should be noted, however, that not all answerbacks follow the preferred sequence described in Recommendation F.60 and allowance should be made for this condition.
+
+**6.4** A different access code should be used depending on the desired mode of operation; either message input or status enquiry.
+
+## **7 Access procedures**
+
+### **7.1 General**
+
+**7.1.1** Two basic access procedures should be provided:
+
+- a) *Interactive operation* – Input from manual calling terminals, where the SFU may return prompt signals.
+
+- b) *Non-interactive operation* – Either input from automatic emitting devices or from subscribers' terminals, where prompt signals from the SFU are not required or are input from another SFU (detection of this type of access will rely on the identification of the calling SFU answerback).
+
+### **7.2 Access from a telex subscriber**
+
+**7.2.1** The originating telex subscriber should establish a call to the SFU by means of normal telex procedures.
+
+**7.2.2** Figure 2 shows the recommended procedures for message deposit in the SFU. The protocol to be followed between the originating telex subscriber and the SFU should be in accordance with Recommendation U.80.
+
+### **7.3 Service request**
+
+#### **7.3.1 Interactive service request**
+
+The originating telex subscriber should be recognized as interactive by the omission of the non-interactive service request (see 7.3.2).
+
+#### **7.3.2 Non-interactive service request**
+
+The originating telex subscriber should indicate that the transmission is from an automatic terminal by commencing the procedure with the non-interactive service request (characters CI).
+
+### **7.4 Message input**
+
+**7.4.1** Provision should be made for both single and multi-addressed calls.
+
+**7.4.2** The SFU should only accept messages for delivery to destination addresses served by that SFU.
+
+**7.4.3** An attention information field may be provided by the SFU to convey the name and address of the recipient.
+
+**7.4.4** The desired class of delivery should be selectable on a destination address basis.
+
+**7.4.5** A message reference number may be returned to the originating subscriber immediately after the date and time information and before message input. In addition, it must be returned after the ITD signal at the end of the transaction. The reference number should comprise up to six numeric characters and cycle through consecutively for follow-on messages within the same transaction with accommodation being made for at least the last two or three digits for this purpose.
+
+**7.4.6** Characters received in the message text with the exception of the WRU signal should be transmitted transparently by the SFU.
+
+**7.4.7** The ITD should be returned to the originating subscriber to indicate that the SFU has accepted the message on receipt of the EOT. Alternatively, an Input Message Acknowledgement signal (IMA) will be sent on receipt of an EOM (ACK) signal.
+
+## **8 Contents of the address line**
+
+### **8.1 Address line**
+
+**8.1.1** Each address to which the message is to be delivered should be provided by the originating subscriber in the address line.
+
+**8.1.2** The address line information may consist of up to five fields:
+
+- a) address to be called;
+- b) expected answerback or part thereof;
+- c) attention information;
+- d) delivery indication;
+- e) Positive Delivery Notification (PDN) request.
+
+![Flowchart showing the general procedure for message deposit into an SFU. The process starts with 'Call set-up to SFU', followed by 'Identification of calling terminal by SFU'. It then enters a loop of 'Input of address(es)' and 'Input of characters'. Decision diamonds check for 'EOM received?', 'EOM (ACK) received?', and 'EOT received?'. If 'EOM received?' is Yes, it loops back to 'Input of address(es)'. If 'EOM (ACK) received?' is Yes, it loops back to 'Input of address(es)'. If 'EOT received?' is Yes, it leads to 'ITD'. If 'EOT received?' is No, it checks 'Clear from caller within 30 seconds?'. If Yes, it leads to 'ITD'. If No, it leads to 'GA'. 'GA' leads to 'Resumption of char. input within 30 seconds?'. If Yes, it loops back to the entry point of the input loop. If No, it leads to 'BMC', which leads to 'Message cancelled by SFU'. Both 'Message cancelled by SFU' and 'ITD' lead to 'Clear by SFU'.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+```
+
+graph TD
+    A[Call set-up to SFU] --> B[Identification of calling terminal by SFU]
+    B --> C[/Input of address(es)/]
+    C --> D[/Input of characters/]
+    D --> E{EOM received?}
+    E -- Yes --> C
+    E -- No --> F{EOM (ACK) received?}
+    F -- Yes --> C
+    F -- No --> G{EOT received?}
+    G -- Yes --> H[/ITD/]
+    G -- No --> I{Clear from caller within 30 seconds?}
+    I -- Yes --> H
+    I -- No --> J[/GA/]
+    J --> K{Resumption of char. input within 30 seconds?}
+    K -- Yes --> D
+    K -- No --> L[/BMC/]
+    L --> M[Message cancelled by SFU]
+    M --> N[Clear by SFU]
+    H --> N
+  
+```
+
+Flowchart showing the general procedure for message deposit into an SFU. The process starts with 'Call set-up to SFU', followed by 'Identification of calling terminal by SFU'. It then enters a loop of 'Input of address(es)' and 'Input of characters'. Decision diamonds check for 'EOM received?', 'EOM (ACK) received?', and 'EOT received?'. If 'EOM received?' is Yes, it loops back to 'Input of address(es)'. If 'EOM (ACK) received?' is Yes, it loops back to 'Input of address(es)'. If 'EOT received?' is Yes, it leads to 'ITD'. If 'EOT received?' is No, it checks 'Clear from caller within 30 seconds?'. If Yes, it leads to 'ITD'. If No, it leads to 'GA'. 'GA' leads to 'Resumption of char. input within 30 seconds?'. If Yes, it loops back to the entry point of the input loop. If No, it leads to 'BMC', which leads to 'Message cancelled by SFU'. Both 'Message cancelled by SFU' and 'ITD' lead to 'Clear by SFU'.
+
+T0102090-92/d02
+
+Figure 2/F.72 – General procedure for message deposit into an SFU
+
+**8.1.3** Each field within an address line and also each address line should be delimited in accordance with Recommendation U.80.
+
+**8.1.4** All fields within an address line except for 8.1.2 a) are optional and may be omitted at the discretion of the originating subscriber.
+
+**8.1.5** The address line(s) should be delimited from the message text by an End of Address (EOA) signal +.
+
+**8.1.6** In general, non-telex addresses should be input in accordance with Recommendation U.80, including the relevant service identifier (e.g. TTX, VTX, PDA)
+
+## **9 Abnormal conditions during message input**
+
+Abnormal conditions encountered during message input should be handled in accordance with Recommendation U.80.
+
+## **10 Message status enquiry**
+
+### **10.1 General procedures**
+
+**10.1.1** A message status enquiry facility should be provided internationally to provide information only in response to a status request from the originator. This message status enquiry point will be accessed by a separate access code to that used for message input.
+
+**10.1.2** When the SFU automatically provides advice of delivery and non-delivery, or a request for positive delivery can be indicated, then the provision of status enquiry facilities is optional.
+
+**10.1.3** Status enquiry information should be maintained preferably for 72 hours.
+
+**10.1.4** The answerback of the message originator should be used for identification and therefore needs to be retained by the SFU for this purpose.
+
+**10.1.5** In the case of multi-address messages, status information may be requested on:
+
+- a) all addresses associated with a message reference number;
+- b) addresses which have not yet received the message;
+- c) addresses specified by the originating telex subscriber.
+
+### **10.2 Status enquiry information field content**
+
+**10.2.1** The status enquiry should contain the following fields:
+
+- a) message reference information;
+- b) a status request;
+- c) address(es).
+
+**10.2.2** The status request indicates the information required (see 10.2.1).
+
+**10.2.3** The address(es) field, see 8.1.2 a), should only be included when status information has been requested for specific addresses.
+
+### **10.3 The status report**
+
+**10.3.1** The status report format should be consistent with the delivery/non-delivery notification advice format as described in Recommendation U.81.
+
+### **10.4 Status report field content**
+
+**10.4.1** The status report should contain the following fields where applicable for each address:
+
+- a) message reference number;
+- b) selection information;
+- c) expected answerback or part thereof;
+
+- d) notification, i.e. not delivered or delivered;
+- e) received answerback;
+- f) reason for non-delivery;
+- g) date and time of delivery;
+- h) duration of call.
+
+**10.4.2** The information contained in fields 10.4.1 e), g) and h) will only be included in a delivery notification whilst the information in field 10.4.1 f) will only be included in a non-delivery notification.
+
+**10.4.3** The information contained in field 10.4.1 f) should indicate to the subscriber the reason why the SFU has been unable to deliver the message to the address detailed in field 10.4.1 b). This information should describe the reason for failure on the latest or final attempt.
+
+**10.4.3.1** When a service signal is received by the SFU, this information shall be placed in the reason field.
+
+**10.4.3.2** Other reasons for non-delivery are:
+
+- a) Wrong answerback received from destination.
+
+The reason field content should be IAB (see 3.2.2).
+
+- b) Clear received by the SFU during message transmission.
+
+The reason field content should be PREM CLR.
+
+- c) Interruption of message transmission caused by receipt of characters at the SFU.
+
+The reason field content should be INTERRUPTED.
+
+- d) Address validation failure.
+
+The reason field content should be REJ.
+
+## **11      Delivery procedure**
+
+The technical aspects of message delivery are described in Recommendation U.81.
+
+**11.1** Clauses 11, 12 and 13 describe procedures for the delivery of international telex messages by an SFU and comprise the following:
+
+- a) message delivery procedures;
+- b) notification procedures;
+- c) delivery retry procedures.
+
+**11.2** The procedures should apply to all classes of message delivery.
+
+**11.3** The priority and time of message delivery should be the responsibility of the SFU that has accepted the input message for delivery.
+
+**11.4** In the case of international interworking between the SFUs, the priority and time of message delivery may be controlled by the originating or destination SFU subject to bilateral agreement between the Administrations concerned.
+
+**11.5** The term “delivery of messages” applies to the forwarding of messages, which were input into an SFU by an originating telex subscriber, to a telex subscriber over the international telex network.
+
+**11.6** The term “notification” applies to the forwarding of an advice of delivery/non-delivery of a message to the originating telex subscriber over an international telex circuit.
+
+### **11.7    Procedures for delivery of messages**
+
+**11.7.1** The sequence of the message forwarding procedure is illustrated in Figure 3.
+
+![Flowchart of the message delivery procedure (Figure 3/F.72). The process starts with 'Call set-up' (11.8.1), followed by 'Called party answerback taken'. A decision 'Called subscriber answerback valid? a)' (11.8.2) follows. If 'No', it goes to 'Ineffective call'. If 'Yes', it proceeds through 'Send SFU identity' (11.8.3), 'Send message identity' (11.8.4), 'Send originating subscriber answerback' (11.8.5), 'Send message text' (11.8.6), and 'Answerback of called subscriber'. A decision 'Answerback comparison?' (11.8.7) follows. If 'No', it goes to 'Ineffective call'. If 'Yes', it proceeds to 'Originating subscriber's answerback' (11.8.8) and 'SFU clear' (11.8.9). Both 'SFU clear' (11.8.9) and 'Ineffective call' lead to 'Notification of delivery/ non-delivery'. A decision 'Delivery retries?' (Recommendation U.40) is shown for the 'Ineffective call' path. A dashed line connects 'Send message text' (11.8.6) to a decision 'See 11.8.6.2', which then leads to the 'Delivery retries?' decision.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+```
+
+graph TD
+    11.8.1[11.8.1 Call set-up] --> 11.8.2{11.8.2 Called subscriber answerback valid? a)}
+    11.8.2 -- No --> Ineffective[Ineffective call]
+    11.8.2 -- Yes --> 11.8.3[11.8.3 Send SFU identity]
+    11.8.3 --> 11.8.4[11.8.4 Send message identity]
+    11.8.4 --> 11.8.5[11.8.5 Send originating subscriber answerback]
+    11.8.5 --> 11.8.6[11.8.6 Send message text]
+    11.8.6 --> 11.8.7{11.8.7 Answerback comparison?}
+    11.8.7 -- No --> Ineffective
+    11.8.7 -- Yes --> 11.8.8[11.8.8 Originating subscriber's answerback]
+    11.8.8 --> 11.8.9[11.8.9 SFU clear]
+    11.8.9 --> Notification[Notification of delivery/ non-delivery]
+    Ineffective --> SFUclear[SFU clear]
+    SFUclear --> DeliveryRetries{Delivery retries? (Recommendation U.40)}
+    DeliveryRetries -- Yes --> CallSetUp[Call set-up]
+    DeliveryRetries -- No --> Notification
+    11.8.6 -.-> See11.8.6.2{See 11.8.6.2}
+    See11.8.6.2 -- Yes --> DeliveryRetries
+  
+```
+
+Flowchart of the message delivery procedure (Figure 3/F.72). The process starts with 'Call set-up' (11.8.1), followed by 'Called party answerback taken'. A decision 'Called subscriber answerback valid? a)' (11.8.2) follows. If 'No', it goes to 'Ineffective call'. If 'Yes', it proceeds through 'Send SFU identity' (11.8.3), 'Send message identity' (11.8.4), 'Send originating subscriber answerback' (11.8.5), 'Send message text' (11.8.6), and 'Answerback of called subscriber'. A decision 'Answerback comparison?' (11.8.7) follows. If 'No', it goes to 'Ineffective call'. If 'Yes', it proceeds to 'Originating subscriber's answerback' (11.8.8) and 'SFU clear' (11.8.9). Both 'SFU clear' (11.8.9) and 'Ineffective call' lead to 'Notification of delivery/ non-delivery'. A decision 'Delivery retries?' (Recommendation U.40) is shown for the 'Ineffective call' path. A dashed line connects 'Send message text' (11.8.6) to a decision 'See 11.8.6.2', which then leads to the 'Delivery retries?' decision.
+
+a) If requested by the originator.
+
+T0103230-93/d03
+
+Figure 3/F.72 – Message delivery procedure
+
+**11.8** The components of message forwarding procedures are as follows:
+
+#### **11.8.1 Call set-up**
+
+- a) Establishment of a connection by an SFU over the international telex network should use normal telex procedures. If a call connect signal is not received, the call attempt should be terminated and a retry made in accordance with Recommendation U.40.
+- b) If service signals are received during the call set-up cycle, the SFU should act in accordance with Recommendation U.40.
+
+#### **11.8.2 Called subscriber answerback validation**
+
+**11.8.2.1** To ensure security of delivery, the answerback of the called subscriber should be compared with the expected answerback of the called subscriber, if supplied by the originating telex subscriber.
+
+**11.8.2.2** One erroneous character displacement shall be tolerated in the validation process of the called subscriber's answerback.
+
+#### **11.8.3 SFU identification**
+
+The SFU identification should consist of the answerback sequence of the SFU, formatted in accordance with Recommendation F.60 and optionally preceded by the code expression CI.
+
+#### **11.8.4 Message identification**
+
+The SFU shall transmit to the called subscriber a message identification sequence issued at the time of input of the message in accordance with 3.1.
+
+#### **11.8.5 Answerback of originating telex subscriber**
+
+The answerback of the originating telex subscriber as received at the time of message deposit should then be sent to the called subscriber where this has been found to conform to Recommendation F.60. Otherwise, the telex SFU shall attach to the answerback of the originating telex subscriber the telex address as determined at the time of message deposit in accordance with Recommendation U.80. These two fields shall be separated by the character / , as follows:
+
+TRANS A LSA/23123456
+
+#### **11.8.6 Message text**
+
+**11.8.6.1** The SFU should transmit to the called subscriber any message header information together with the stored message in the format in which it was originated by the calling subscriber. The EOM/EOT separators and the WRU signal shall not be transmitted.
+
+**11.8.6.2** If any signal is received on the backward path during the message text delivery, transmission of the message should be stopped for two seconds. If during that time further signals or a clearing condition is received, the call shall be cleared, message delivery deemed unsuccessful and action taken in accordance with 3.9. If no further signals are received on the backward path during that time, transmission of the message shall be resumed.
+
+#### **11.8.7 Called subscriber answerback comparison**
+
+Following message transmission, the answerback of the called subscriber should be taken and compared with that received at the start of message delivery. If they are the same, the delivery of the message shall be deemed successful. Otherwise, the answerback of the called subscriber shall be taken again for comparison. If there is a second mismatch, the delivery of the message should be considered as unsuccessful and further delivery attempts shall be made in accordance with clause 13.
+
+#### **11.8.8 Answerback of originating telex subscriber**
+
+The answerback of the originating subscriber shall then be sent to the called subscriber.
+
+#### **11.8.9 Call clearing sequence**
+
+Following the transmission of its answerback, the SFU should clear the call using normal telex clearing procedures. However, in the case of delivery to a Teletex destination, clearing procedures should be in accordance with Recommendations F.201 and U.201.
+
+## **12 Notification procedures**
+
+### **12.1 Types of notification**
+
+The types of notification are shown in 3.9.
+
+### **12.2 Notification delivery procedures**
+
+**12.2.1** Status reports should be returned in response to a status request.
+
+**12.2.2** All other types of notification should be delivered using the procedure described for telex message forwarding in 11.7 and 11.8.
+
+**12.2.3** To ensure security of delivery of the notification, the answerback of the called subscriber should be compared with the answerback of the originating subscriber received at the time of message input.
+
+## **13 Delivery retry procedures**
+
+**13.1** The principles of Recommendation U.40 should be applied for all delivery/notification retry requirements.
+
+**13.2** The action to be taken when a notification cannot be delivered should be the responsibility of the Administration operating the SFU as described in 3.9.
+
+### **13.3 Recorded message from the called subscriber**
+
+**13.3.1** If the recorded message is followed by clear, the message shall be considered undeliverable.
+
+**13.3.2** The action to be taken by the SFU if the recorded message is not followed by a clear is for further study.
+
+## **14 Contents of delivery/non-delivery notifications**
+
+**14.1** The delivery/non-delivery notification should contain the same fields as shown for the status report in 10.4.1.
+
+## **15 Internationally interconnected store and forward units**
+
+The international interconnection of telex SFUs should be implemented using the procedures and functions of the Message Handling Services in accordance with the F.400-Series of Recommendations.
+
+# ITU-T RECOMMENDATIONS SERIES
+
+- Series A Organization of the work of the ITU-T
+- Series B Means of expression: definitions, symbols, classification
+- Series C General telecommunication statistics
+- Series D General tariff principles
+- Series E Overall network operation, telephone service, service operation and human factors
+- Series F Non-telephone telecommunication services**
+- Series G Transmission systems and media, digital systems and networks
+- Series H Audiovisual and multimedia systems
+- Series I Integrated services digital network
+- Series J Transmission of television, sound programme and other multimedia signals
+- Series K Protection against interference
+- Series L Construction, installation and protection of cables and other elements of outside plant
+- Series M Maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits
+- Series N Maintenance: international sound programme and television transmission circuits
+- Series O Specifications of measuring equipment
+- Series P Telephone transmission quality, telephone installations, local line networks
+- Series Q Switching and signalling
+- Series R Telegraph transmission
+- Series S Telegraph services terminal equipment
+- Series T Terminals for telematic services
+- Series U Telegraph switching
+- Series V Data communication over the telephone network
+- Series X Data networks and open system communication
+- Series Z Programming languages

marked/F/T-REC-F.720-199208-I_PDF-E/raw.md

@@ -0,0 +1,392 @@
+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**CCITT**
+
+THE INTERNATIONAL  
+TELEGRAPH AND TELEPHONE  
+CONSULTATIVE COMMITTEE
+
+**F.720**
+
+(08/92)
+
+**TELEMATIC, DATA TRANSMISSION,  
+ISDN BROADBAND, UPT AND  
+TELECONFERENCE SERVICES:**
+
+**OPERATIONS AND QUALITY OF SERVICE**
+
+---
+
+**VIDEOTELEPHONY SERVICES – GENERAL**
+
+![CCITT logo: A globe with the letters CCITT.](84a1d09fb489061482111515543b60dc_img.jpg)
+
+CCITT logo: A globe with the letters CCITT.
+
+**Recommendation F.720**
+
+---
+
+# FOREWORD
+
+The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988).
+
+Recommendation F.720 was prepared by Study Group I and was approved under the Resolution No. 2 procedure on the 4th of August 1992.
+
+---
+
+# CCITT NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication Administration and a recognized private operating agency.
+
+# **VIDEOTELEPHONY SERVICES – GENERAL**
+
+(1992)
+
+The CCITT,
+
+*considering*
+
+- (a) that videotelephony services have been introduced in pilot form in various network environments in a number of countries;
+- (b) that videotelephony services are liable to be demanded by users around the whole world;
+- (c) that users will expect an acceptable minimum Quality of Service;
+- (d) that users will expect an ease of use comparable to ordinary telephony;
+- (e) that users will expect a high level of interoperability with other audiovisual services and with telephony,
+
+*adopts*
+
+the subsequent Recommendation dealing with the general description for videotelephony services.
+
+The relevant attributes and values are incorporated as part of each dedicated service description.
+
+# **CONTENTS**
+
+- 1 *Introduction*
+- 2 *Definition*
+- 3 *Description*
+- 4 *Procedures*
+- 5 *Network aspects*
+- 6 *Terminal aspects*
+- 7 *Quality of Service*
+- 8 *Interworking and intercommunication requirements*
+
+# **1 Introduction**
+
+The purpose of this Recommendation is to define and describe the general features and attributes of the videotelephony service regardless of the network environment where the service might be provided. The videotelephony service is classified in the following two main categories:
+
+- videotelephony service for narrow-band networks;
+- videotelephony service for broadband networks.
+
+The intention is to assign a dedicated Recommendation for each type of videotelephony service in specific networks. The dedicated Recommendation is due to contain a description in detail of the service concerned with all relevant characteristics and attributes. Recommendation F.721 covers the basic videotelephony service in the Integrated services digital network (ISDN) due to this classification. Dedicated service Recommendations for higher quality videotelephony services are for further study. The higher quality videotelephony service will not necessarily employ any fixed information transfer rate as variable bit rate coding may be used. The classification of videotelephony services is depicted in Figure 1/F.720.
+
+![A hierarchical diagram titled 'Classification of videotelephony services'. At the top level, a box labeled 'Videotelephony services' is enclosed in a dashed rectangle labeled '(Recommendation F.720)'. Below this box, two lines branch down to two separate boxes: 'Videotelephony for narrowband networks' on the left and 'Videotelephony for broadband networks' on the right. Below the 'narrowband' box, a line leads to a box labeled 'Videotelephony teleservice for ISDN (Recommendation F.721)'. Below the 'broadband' box, a line leads to a box labeled 'Broadband videotelephony services (Recommendation F.722)'. In the center, between the two bottom boxes, is a box labeled 'Note 2'.](2fa4a1bf91d0f34e87c689fbc1211fe3_img.jpg)
+
+```
+
+graph TD
+    subgraph F720 [Recommendation F.720]
+        VS[Videotelephony services]
+    end
+    VS --> VNN[Videotelephony for narrowband networks]
+    VS --> VBN[Videotelephony for broadband networks]
+    VNN --> VTISDN[Videotelephony teleservice for ISDN Recommendation F.721]
+    VBN --> BVS[Broadband videotelephony services Recommendation F.722]
+    Note2[Note 2]
+    VTISDN --- Note2 --- BVS
+  
+```
+
+A hierarchical diagram titled 'Classification of videotelephony services'. At the top level, a box labeled 'Videotelephony services' is enclosed in a dashed rectangle labeled '(Recommendation F.720)'. Below this box, two lines branch down to two separate boxes: 'Videotelephony for narrowband networks' on the left and 'Videotelephony for broadband networks' on the right. Below the 'narrowband' box, a line leads to a box labeled 'Videotelephony teleservice for ISDN (Recommendation F.721)'. Below the 'broadband' box, a line leads to a box labeled 'Broadband videotelephony services (Recommendation F.722)'. In the center, between the two bottom boxes, is a box labeled 'Note 2'.
+
+T0102080-92
+
+*Note 1* – In broadband ISDN the service offerings may also comprise videotelephony services using low bit rates.
+
+*Note 2* – In the future, videotelephony services may be provided also other networks requiring new dedicated service Recommendations.
+
+FIGURE 1/F.720  
+**Classification of videotelephony services**
+
+# 2 Definition
+
+**Videotelephony service** is an audiovisual conversational teleservice providing bidirectional symmetric real-time transfer of voice and moving colour pictures between two locations (person-to-person) via the networks involved. The minimum requirement is that under normal conditions the picture information transmitted is sufficient for the adequate representation of fluid movements of a person displayed in head and shoulders view (see Note).
+
+*Note* – The smoothness of the movements in the reproduced picture is essentially dependent on the amount of motion with respect to the transfer rate of transmitted picture information. The above requirements are supposed to be met under such conditions where the amount of motion is limited or the throughput is high enough not to impair the received picture. Degradation is likely to appear as increased blurring and jerkiness in the reproduced picture. Besides this, other artifacts may occur.
+
+# 3 Description
+
+## 3.1 General description
+
+The plain videotelephony service includes only the basic user requirements, namely speech and motion picture with essential controls and indications; the service can be enhanced with options providing auxiliary facilities such as transmission of high resolution still images of documents, photographs, drawings, charts, objects, etc. (see Note).
+
+*Note* – Speech supported only by still picture transmission and/or telewriting is not considered as a part of the videotelephony service. This type of communication may either be considered as a separate audiovisual service or as a form of audiographic conference service in a point-to-point configuration.
+
+The videotelephony service is likely to be used in much the same way as the ordinary telephone service for individual communication, the enhancement being in the visibility of the communicating parties which implies a number of possible new applications.
+
+An essential feature of the service is that it is always provided in conjunction with ordinary telephony allowing the user to intercommunicate with all kinds of audiovisual services by using merely the speech communication facility of a videotelephone terminal. In other words, videotelephone terminals must be capable of supporting telephony.
+
+A videotelephony service may also be used in applications such as communication of speech – and hearing – impaired persons using sign language and remote surveillance where the speech communication facility is of minor importance.
+
+In case the service is provided in a network and terminal environment which offers a number of different quality levels depending, among others, on the transmission medium used and respective charging, it must be possible for the user to select the level/mode of operation and/or type of videotelephony service he/she wishes and also change it during the call if provided by the network or supported by the terminals. The latter option may be provided as a supplementary service.
+
+Two different types of call shall be possible:
+
+- point-to-point calls;
+- multipoint calls (see Note).
+
+*Note* – For multipoint calls a unit for mixing speech signals and/or combining video signals is required. This will be defined in another context later.
+
+## 3.2 *Description of various videotelephony services*
+
+Two primary videotelephony service categories have been identified, for narrow-band networks and for broadband networks. The principle features of either type of service are described below.
+
+### 3.2.1 *Videotelephony service for narrow-band networks*
+
+The videotelephony service for narrow-band networks provides end-to-end communication of moving colour pictures with spatial resolution, temporal resolution and quality equivalent to that obtainable by coding the video signal according to Recommendation H.261 (QCIF and CIF format).
+
+The videotelephone service may be optionally enhanced by facilities such as the transfer of still pictures, graphics, text and end-to-end control messages.
+
+A basic videotelephone teleservice for the narrow-band ISDN has been fully standardized according to Recommendations I.210 and I.240. The stage 1 description for the videotelephony teleservice for ISDN is contained in Recommendation F.721.
+
+In the future, basic videotelephony services for other narrow-band networks (e.g. radio mobile networks, private networks) could be envisaged.
+
+### 3.2.2 *Videotelephony service for broadband networks*
+
+The videotelephony service for broadband networks provides end-to-end communication of moving colour pictures with high spatial and temporal resolution and video quality equivalent to conventional TV standards (PAL, SECAM, NTSC) or better and enhanced voice/sound quality, possibly stereo transmission and optionally facilities for the transfer of still pictures, graphics, text and end-to-end control messages.
+
+## 3.3 *Applications related to videotelephony*
+
+The videotelephony service can be utilized in a broad range of applications depending on the Quality of Service for audio and/or video that can be achieved in different types of services.
+
+A videotelephony service employing the bearer capabilities of broadband networks is expected to meet the needs of the subsequently listed applications. Because of the high video quality, this service provides, besides the means for face-to-face dialogue, the possibility to transfer any kind of moving scenes. Also pictures of three-dimensional objects, graphic material, e.g., sketches, drawings, photographs and documents containing text and graphics can be transferred without any restrictions. Commercial and domestic scenes, instruction procedures and films can be transferred to the communication partner.
+
+The constraints imposed by limited transfer capability of narrow-band networks on spatial and temporal image resolutions make certain types of communication less applicable to the videotelephony service for narrow-band networks.
+
+Taking into account the aspects mentioned above, the following principle applications of videotelephony are possible among others:
+
+- a) face-to-face dialogues involving at least head-and-shoulder images;
+- b) dialogue including interactive viewing of documents such as sketches, diagrams or charts and objects that can be shown on the screen;
+- c) access of the user to videoconferences;
+- d) remote video surveillance;
+- e) communication between hearing and speech impaired persons using the sign language.
+
+Based on these examples, other enhanced videotelephone applications may also emerge.
+
+The user should be given the possibility to select the essential parameters best suiting his specific application. For instance, in applications b) high spatial resolution is required and on the other hand in e), good motion tolerance is important. Moreover, the transfer rate used for audio should be selectable, in particular when it has charging or video quality implications.
+
+## 3.4 *Supplementary services and enhancements*
+
+The same spectrum of supplementary services supporting telephony is in principle applicable for videotelephony.
+
+Other supplementary services or enhancements, dedicated to videotelephony, e.g. videotelephony conference services, are for further study. Relevant enhancements are those supporting the transfer of high resolution still pictures and graphics information in a variety of formats like digitized video or other standard document formats. A paper/film scanner or video frame capture may be used as an image input source. Besides this, the possibility to access electronic mail or videotex services with a videotelephone terminal may be supported.
+
+## 3.5 *Specific terminology*
+
+*Fall back:* Procedures performed either by the network or by the calling terminal that allows the calling user to be connected in any case with the called user at any terminal where the call is offered (3.1 kHz telephone terminal or videotelephone terminal).
+
+# 4 **Procedures**
+
+## 4.1 *General*
+
+The call control procedures should be from the user's point of view as simple as for ordinary telephony in order to achieve good acceptance. The audible signalling tones must have the same meaning as for telephony. Visual guidance with the aid of the videotelephone terminal display may play an important role in the invocation and operation of the service.
+
+## 4.2 *Provision/withdrawal*
+
+Provision of the service will be by arrangement with the relevant Administration.
+
+## 4.3 *Normal procedures*
+
+### 4.3.1 *Activation/deactivation/registration*
+
+Not applicable.
+
+### 4.3.2 *Invocation and operation*
+
+#### 4.3.2.1 *Call request*
+
+The call set-up must be available for the user as a single operation, preferably not different from that for telephony.
+
+As a user option, the terminal can instead be set such that video communication is established only when requested by the users. If a call attempt involves more than one transmission channel, and not all transmission channels are available for the call (for whatever reasons), the call shall still proceed with the best level of video quality available. It must be possible for the user to select the transmission rate or other relevant parameters affecting on the service quality and respective service and tariff class.
+
+Call set-up from the user's point of view can be optionally executed by initiating first the voice communication and adding the videocommunication after the connection has been established.
+
+#### 4.3.2.2 *Call release*
+
+In general, the procedure for disconnecting a videotelephone call shall be the same as for ordinary telephony. Speech and image shall be disconnected simultaneously.
+
+#### 4.3.2.3 *Change of service*
+
+During a single call the change of service can be executed unrestricted as desired by the users with the aid of in-call modification procedures if provided by the network. A change of selected audiovisual capabilities is provided by in-band signalling and protocols.
+
+#### 4.3.2.4 *Videotelephony conference call*
+
+Conference facilities supporting the videotelephony service are necessary either in the network and/or at the user premises.
+
+The procedures and functions are for further study.
+
+#### 4.3.2.5 *Controls and indications*
+
+### 4.3.3 *User guidance*
+
+User guidance can take place in the form of dialogue between the system and the user: information concerning the status of the call can be displayed on the screen or on another possible display of a videotelephone terminal (both the calling and called party can apply). Guidance may be based on the display of alphanumeric characters in a selectable language, or by other visual means accompanied by appropriate audible announcements taking into account the needs of hearing and speech impaired users.
+
+The audible call progress signals used in any videotelephony service shall comply with those of ordinary telephony. Visual counterparts of the audible call progress signals should be defined and standardized.
+
+It must be possible for both the calling and called party to switch on and off the outgoing picture without disconnecting the connection allocated for video transmission. In case the outgoing picture is suppressed, a predetermined substitutional pictogram should be displayed on the screen of the remote terminal.
+
+Using a specific control, a user should be able to display the outgoing picture on the screen of the videotelephone terminal, either prior to call set-up or during the call (self view).
+
+### 4.3.4 *Auxiliary functionalities*
+
+It should be possible to display the picture of the communicating parties on the screen of either terminal, although not necessarily simultaneously.
+
+Hands-free and loudspeaking modes are desirable and may be provided in videotelephone terminals.
+
+Besides the suppression of the outgoing video information, it should be possible to mute the audio channel as desired by the user. The other party may receive an indication on the activated muting.
+
+## 4.4 *Exceptional procedures*
+
+In case of decreasing of service quality (e.g. due to high error rate or other network reasons) appropriate indication should be given for both parties, even if the problems concern only one direction.
+
+# 5 **Network aspects**
+
+For further study.
+
+# 6 **Terminal aspect**
+
+## 6.1 *General systems requirements*
+
+In order to perform the basic functions necessary for the videotelephony service the terminal equipment must include devices capable of:
+
+- capturing participant's picture(s);
+- displaying remote user's picture(s);
+- capturing audio;
+- reproducing audio;
+- audio coding;
+- video coding;
+- management of network interfaces.
+
+The terminal equipment also includes devices capable of performing the following functions:
+
+- user control;
+- user indication;
+- self view;
+- testing.
+
+Terminals intended to be used in multipoint connections may need additional basic functions related to multipoint operation. These functions are for further study.
+
+## 6.2 *Videotelephone terminal equipment*
+
+The basic videotelephone terminal equipment may include only the basic elements listed in 6.1.
+
+Possible enhancements to the equipment are:
+
+- orientable camera and zoom;
+- still picture camera;
+- interfaces for an additional camera, an additional screen or a video recorder;
+- remote control of a distant camera for some specific applications;
+- keyboard for the videotex service;
+- telewriting.
+
+This list is not exhaustive and is only given as a set of examples. As a general rule, the number of controls that a user has to operate should be kept to a minimum. Training should not be necessary for using the terminal. Clear and concise instructions should be given, for instance on the screen, especially for the supplementary services with which the user may not be very familiar.
+
+# 7 Quality of Service
+
+## 7.1 Picture quality
+
+Picture quality is a measure of the ability of a video transmission system to accurately reproduce moving scenes. Video quality objectives are generally expressed in terms of spatial and temporal resolution. Optimization and more accurate definition of the picture quality requires further study.
+
+The recovery time for pictures built-up when the video source is changed should be low enough not to impair the service quality. Further studies are required.
+
+### 7.1.1 Videotelephony service for narrow-band networks
+
+Optimization and more accurate definition of the picture quality including motion tolerance require further study (see Note).
+
+*Note* – The urgent need to accomplish both subjective and objective methods to evaluate the quality of a heavily compressed motion picture is widely identified.
+
+### 7.1.2 Videotelephony service for broadband networks
+
+Picture quality must be at least as that of high quality domestic TV-receivers (see among others, CCIR Recommendation R.601).
+
+## 7.2 Audio quality
+
+The minimum speech quality must be as good as that of ordinary PCM telephony based on either A-law or  $\mu$ -law encoding (at least no significant impairment is allowed with regard to Recommendation G.711).
+
+Efficient echo control must be provided in the local facilities as echoes may seriously impair the audio quality.
+
+## 7.3 Synchronization of speech and lip movement (lip synchronization)
+
+Lip synchronizm must be ensured. There should be no subjectively discernible difference of the speech signal with regard to the video.
+
+## 7.4 Overall delay
+
+The overall delay is defined to consist of the one-way delay of the transmission path and the characteristic delay of a videotelephone terminal. Characteristic delay of a videotelephone terminal is the delay introduced by the terminal when only lips and eyes of the talking user are moving.
+
+The overall effect on quality by the delays introduced by videocodecs and transmission facilities needs to be taken into account in the service because increased delays may impair the user acceptability.
+
+Maximum allowable delay including the maximum number of satellite hops are left for further study.
+
+For videotelephony services using separated digital channels it is possible that one or more channels are routed via terrestrial paths while the other(s) is (are) routed via satellite. In these cases the resynchronization is performed by the terminal. The Quality of Service is the same as if all channels were routed via satellite.
+
+## 7.5 Sensitivity to transmission errors
+
+The maximum allowable degradation of service due to transmission errors needs to be defined. Further study required.
+
+# 8 Interworking and intercommunication requirements
+
+The following interworking/intercommunication situations have been identified:
+
+- intercommunication with 3.1 kHz and 7 kHz telephony services;
+- intercommunication between videotelephony services on same and different networks;
+- intercommunication with other audio and visual services.
+
+## 8.1 Intercommunication/interworking with telephony services
+
+### 8.1.1 General principles
+
+Considering:
+
+- the fact that at the beginning of the introduction of the videotelephony service the number of videotelephone subscribers is negligible compared with the number of telephone subscribers;
+- that a user may have only one type of audiovisual terminal such as videotelephone, 7 kHz telephone or 3.1 kHz telephone,
+
+as a conclusion, a fundamental requirement must be met in order to avoid the situation where videotelephone subscribers can only communicate in a kind of closed user group. Therefore, it is essential, as a default procedure, that every videotelephone subscriber be able to reach from his videotelephone terminal every telephone subscriber.
+
+This condition must be met regardless of the technology applied in the local exchange to which the telephone subscriber is connected. This can lead to interworking or intercommunication situations.
+
+From the user's point of view, a very important attribute of the intercommunication/interworking solutions is a short call set-up delay. Therefore, when a solution is being developed, the set-up delay should be considered as a high priority performance characteristic.
+
+If in case of intercommunication, a videotelephone communication cannot be provided, a telephone call should be initiated. If then no call can be established, an appropriate cause indication shall be given to the calling user.
+
+Every telephone terminal must be able to reach every videotelephone terminal and vice versa. This requirement implies that a videotelephone terminal will be a multiservice terminal supporting also telephone calls as well as videotelephone calls.
+
+### 8.1.2 Description
+
+Terminals for all videotelephony service classes and cases shall, in any case, support voice encoding in accordance with Recommendation G.711 (A-law and  $\mu$ -law). A videotelephony service may include additional speech encoding as a basic or optional feature depending on the precise service and mode.
+
+Videotelephony service shall intercommunicate with 3.1 kHz, 7 kHz or possibly 15 kHz telephony. The following cases are considered essential:
+
+- 1) Under the user's control, videotelephony requesting outgoing calls shall be able to initiate:
+  - videotelephone calls;
+  - ordinary 3.1 kHz telephone calls;
+  - telephone calls with extended bandwidth of 7 kHz or possibly 15 kHz, if supported by the terminal of the calling party.
+- 2) For incoming calls, a videotelephone terminal shall be able to respond on a default basis to:
+  - videotelephone calls;
+  - ordinary 3.1 kHz telephone calls;
+  - telephone calls with extended bandwidth of 7 kHz or possibly 15 kHz, if supported by the terminal of the called party.
+
+## 8.2 *Intercommunication between videotelephony services on different networks*
+
+Intercommunication between videotelephony services on the existing and future networks should also be provided. Further studies are required.
+
+## 8.3 *Intercommunication with other audiovisual services*
+
+G.711 telephony is the minimum requirement of intercommunication between all types of audiovisual services. Intercommunication or interworking with various types of videoconferencing should be provided. The audiovisual quality is in this case the best common mode. Further studies are required.

marked/F/T-REC-F.731-199707-I_PDF-E/raw.md

@@ -0,0 +1,271 @@
+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.731**
+
+(07/97)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Audiovisual services
+
+---
+
+**Multimedia conference services in the ISDN**
+
+ITU-T Recommendation F.731
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1–F.109          |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| MOBILE SERVICE                                                  | F.110–F.159        |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| TELEMATIC SERVICES                                              | F.160–F.399        |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400–F.499        |
+| DIRECTORY SERVICES                                              | F.500–F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550–F.599        |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600–F.699        |
+| <b>AUDIOVISUAL SERVICES</b>                                     | <b>F.700–F.799</b> |
+| ISDN SERVICES                                                   | F.800–F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850–F.899        |
+| HUMAN FACTORS                                                   | F.900–F.999        |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+# **ITU-T RECOMMENDATION F.731**
+
+# **MULTIMEDIA CONFERENCE SERVICES IN THE ISDN**
+
+## **Source**
+
+ITU-T Recommendation F.731 was prepared by ITU-T Study Group 16 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 10th of July 1997.
+
+## FOREWORD
+
+ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, the ITU had/had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 1997
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU.
+
+## CONTENTS
+
+|                                                    | Page |
+|----------------------------------------------------|------|
+| 1 Introduction .....                               | 1    |
+| 4.3 Configuration.....                             | 1    |
+| 4.4 Roles of the participants .....                | 1    |
+| 4.5 Terminal aspects.....                          | 1    |
+| 6.2.7 Conference management procedures .....       | 2    |
+| 7.2 List of service profiles .....                 | 2    |
+| 8 Interworking/intercommunication.....             | 2    |
+| 9 Attributes values.....                           | 3    |
+| 9.1 General .....                                  | 3    |
+| 9.2 Service independent attributes.....            | 3    |
+| 9.3 Service specific attributes.....               | 4    |
+| Annex A – Multipoint Conference Units (MCUs) ..... | 5    |
+
+
+
+# **MULTIMEDIA CONFERENCE SERVICES IN THE ISDN**
+
+*(Geneva, 1997)*
+
+## **1 Introduction**
+
+This Recommendation describes the Multimedia Conference Services supported by an ISDN. It relies on Recommendation F.702 for the main body of the description, and only gives the specific complements relevant to the ISDN, which derive from its capabilities and its limitations. Thus when reading this Recommendation, it is necessary to refer back to Recommendation F.702. The numbers of the clauses are those of Recommendation F.702, and thus they do not form a continuous sequence because only a few clauses need a specific complement for the ISDN. In addition there is a new clause 9 on the attributes for the various profiles.
+
+### **4.3 Configuration**
+
+In the ISDN, all connections are bidirectional symmetric. When several B-channels are used, they are synchronized through the frame alignment process of Recommendation H.221, so that a single composite channel is formed, where audio, video, data and control signals are multiplexed and are allocated specific subchannels. Data and enhanced control signals may be multiplexed in a common packet subchannel supporting the T.120-Series protocol (whereas basic control signals are in the BAS channel of Recommendation H.221).
+
+The various possible configurations supported by these connections are as follows:
+
+- a) point-to-point between two terminals;
+- b) multichannel multipoint for the continuous presence mode;
+- c) shared channel around one or more MCUs: the audio channels are mixed, the data signals are multiplexed (if present) in a common T.120 subchannel; this is the usual mode in the case of an audiographic conference or of CDH without video (see 7.1/F.702); when video is present, the pictures from the different sources are combined into a single picture with several windows;
+- d) switched multipoint operation: the audio signals or the video signals or both are switched in the MCU(s); this is the usual mode for the videoconference service, with mixed audio and a single switched video picture; multiple switched video subpictures are for further study.
+
+### **4.4 Roles of the participants**
+
+The basic control signals in the BAS channel allocate the roles of Chairman and controller jointly; they can only be separated inside the terminal equipment. The T.120-Series protocol allows separate allocation of call control, chair control and facility control.
+
+### **4.5 Terminal aspects**
+
+The normal audio mode for conferencing services is wideband audio conforming to Recommendation G.722. A G.711 codec should also be present for interworking purposes. G.728 coding may also be used in interworking or fallback situations, or temporarily to leave a larger bandwidth to the video or to the data subchannels, e.g. while showing an object or transmitting a document.
+
+Video codecs should conform to Recommendation H.261. The possible use of higher quality codecs is for further study.
+
+#### **6.2.7 Conference management procedures**
+
+All terminals should conform to the procedures in Recommendation H.242. Multipoint procedures are those of Recommendation H.243.
+
+Media components other than audio and video should be transmitted on a common data subchannel supporting the T.120-Series protocol.
+
+### **7.2 List of service profiles**
+
+The following service profiles may be offered over an ISDN.
+
+- 1) *Videoconference services*
+  - Profiles 1a: Basic videoconference service on two B-channels; terminals should conform to Recommendation H.320;
+  - Profiles 1b: Standard videoconference service on six B-channels (or one H0-channel); terminals should conform to Recommendation H.320;
+  - Profile 1c: Enhanced videoconference service; for further study;
+  - Profile 1d: High quality videoconference service; for further study.
+- 2) *Audiographic conference services*
+  - Profiles 2: All audiographic conference services use wideband audio conforming to Recommendation G.722 and a data subchannel supporting the T.120-Series protocol.
+- 3) *Cooperative document handling services*
+  - Profiles 3: All cooperative document handling services have audio to one or more of the Recommendations G.711, G.722, G.728; they have a data subchannel supporting the T.120-Series protocol, and in particular T.127 for file transfer; other data functions are for further study; H.261 video is optional.
+- 4) *Videophone conference supplementary services*
+  - Profile 4b: Basic videophone conference supplementary service; this supplementary service applies to basic videophone terminals on one or two B-channels, and does not require any specific enhancements to the terminals; these terminals conform to Recommendation H.320, have G.728 and/or G.722 audio codecs (and G.711 for interworking purposes) and H.261 video codecs; on two B-channels, the profile is the same as Profile 1a except that G.722 coding is only optional instead of mandatory.
+
+## **8 Interworking/intercommunication**
+
+All terminals have the media component audio. The basic common audio mode is G.722. However, some videophone terminals (and possibly some CDH terminals) may not have that capability; in that case G.711 is used, or alternatively G.728 if all terminals in the conference have that capability.
+
+For the media component video, all terminals which support it use H.261 coding. They will always be able to communicate with this coding algorithm, by aligning the bit rate of the video subchannel on the lowest bit rate. If the resulting quality is not sufficient, then a higher bit rate may be chosen, with some terminals relegated to secondary status and participating with sound (and possibly data) only.
+
+For the other media components, all terminals using them have a common data subchannel with the T.120 protocol. The bit rate of the subchannel will be aligned on the terminal with the lowest bit rate capability. However, this does not imply that all terminals will have a common media component. For instance a group of participants may be able to exchange facsimile while another group (overlapping or not) may exchange still pictures.
+
+## 9 Attributes values
+
+### 9.1 General
+
+In the ISDN, only point-to-point independent channels can be established. When several B-channels are used in a connection, they are based on separate independent calls and synchronized in-band. Similarly, in a multipoint configuration, each connection between a terminal and an MCU or between two MCUs is an independent point-to-point connection. The same also applies for H0-channels.
+
+When two or more B- (or H0-) channels are needed to support a connection, one of them supports the audio and BAS control subchannels; the call for establishing this channel is referred to as Call 1. Except when otherwise stated, the values of the attributes are the same for Call 1 and for the other calls involved in the connection.
+
+### 9.2 Service independent attributes
+
+The following attribute values are applicable to all multimedia conference service profiles.
+
+#### 1) *Low layer attributes*
+
+|   | Attributes                     | Values                                                                                                             |
+|---|--------------------------------|--------------------------------------------------------------------------------------------------------------------|
+| 1 | Transfer mode                  | Circuit                                                                                                            |
+| 2 | Transfer rate                  | 64 kbit/s                                                                                                          |
+| 3 | Transfer capability            | Call 1: unrestricted digital information with tones/announcements<br>Other calls: unrestricted digital information |
+| 4 | Structure                      | 7 kHz integrity                                                                                                    |
+| 5 | Establishment of communication | Demand or reservation                                                                                              |
+| 6 | Symmetry                       | Bidirectional symmetric                                                                                            |
+| 7 | Configuration of call          | Point-to-point                                                                                                     |
+
+#### 2) *Access attributes*
+
+|     | <b>Attributes</b>                    | <b>Values</b>                                                |
+|-----|--------------------------------------|--------------------------------------------------------------|
+| 8   | Access channel and rate              | D(16) or D(64) for signalling,<br>B(64) for user information |
+| 9.1 | Signalling access protocol, Layer 1  | Rec. I.430/I.431                                             |
+| 9.2 | Signalling access protocol, Layer 2  | Rec. Q.921                                                   |
+| 9.3 | Signalling access protocol, Layer 3  | Rec. Q.931                                                   |
+| 9.4 | Information access protocol, Layer 1 | Rec. H.221                                                   |
+| 9.5 | Information access protocol, Layer 2 | Rec. H.230                                                   |
+| 9.6 | Information access protocol, Layer 3 | Rec. H.242, Rec. H.243                                       |
+
+### **9.3 Service specific attributes**
+
+The following attribute values are applicable to the communication as a whole, even when two or more separate calls are established in the network to support the required connection. They are generally dependent upon the multimedia conference service profiles.
+
+#### 3) *High layer attributes*
+
+|    | <b>Attributes</b>          | <b>Values</b>                                                                                                                                                                                |
+|----|----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 10 | Type of user information   | Audio (in Call 1 only) + video<br>and/or data                                                                                                                                                |
+| 11 | Layer 4 protocol functions |                                                                                                                                                                                              |
+| 12 | Layer 5 protocol functions |                                                                                                                                                                                              |
+| 13 | Layer 6 protocol functions | Rec. G.711, Rec. G.722 or<br>Rec. G.728 for audio<br>Rec. H.261 for video (profiles 1, 4,<br>optional for profile 3)<br>T.120-Series for data (profiles 2, 3,<br>optional for profiles 1, 4) |
+| 14 | Layer 7 protocol functions |                                                                                                                                                                                              |
+
+#### 4) *General attributes*
+
+|    | <b>Attributes</b>                             | <b>Values</b>                                                                                                                                                                                                                        |
+|----|-----------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 15 | Supplementary services provided               | For further study                                                                                                                                                                                                                    |
+| 16 | Quality of service                            | Audio: 7 kHz telephony for profiles 1, 2 telephone quality for profiles 3, 4<br>Video: see 5.3.2.2/F.702<br>Synchronization of audio and video: no subjectively discernible delay between sound and image<br>Data: for further study |
+| 17 | Intercommunication/interworking possibilities | With other multimedia conference services<br>with videophone service<br>with telephony<br>with other services: for further study                                                                                                     |
+| 18 | Operation and commercial aspects              | For further study                                                                                                                                                                                                                    |
+
+## ANNEX A
+
+### **Multipoint Conference Units (MCUs)**
+
+MCUs shall conform to Recommendation H.231 and use the procedures of Recommendation H.243.
+
+In a conference, all connections have the same overall bit rate and the same allocation of bit rates to the audio, video and data subchannels, whether between a terminal and an MCU or between MCUs. The exception to this is the connection to a terminal with secondary status, which cannot use all the subchannels and may thus be connected at a smaller bit rate. The possibility of additional or broader subchannels on inter-MCU connections is for further study.
+
+
+
+# ITU-T RECOMMENDATIONS SERIES
+
+- Series A Organization of the work of the ITU-T
+- Series B Means of expression: definitions, symbols, classification
+- Series C General telecommunication statistics
+- Series D General tariff principles
+- Series E Overall network operation, telephone service, service operation and human factors
+- Series F Non-telephone telecommunication services**
+- Series G Transmission systems and media, digital systems and networks
+- Series H Audiovisual and multimedia systems
+- Series I Integrated services digital network
+- Series J Transmission of television, sound programme and other multimedia signals
+- Series K Protection against interference
+- Series L Construction, installation and protection of cables and other elements of outside plant
+- Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits
+- Series N Maintenance: international sound programme and television transmission circuits
+- Series O Specifications of measuring equipment
+- Series P Telephone transmission quality, telephone installations, local line networks
+- Series Q Switching and signalling
+- Series R Telegraph transmission
+- Series S Telegraph services terminal equipment
+- Series T Terminals for telematic services
+- Series U Telegraph switching
+- Series V Data communication over the telephone network
+- Series X Data networks and open system communication
+- Series Z Programming languages

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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.733**
+
+(09/2005)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Audiovisual services
+
+---
+
+**Service description and requirements for  
+multimedia conference services over IP  
+networks**
+
+ITU-T Recommendation F.733
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+## **TELEGRAPH SERVICE**
+
+|                                                                 |             |
+|-----------------------------------------------------------------|-------------|
+| Operating methods for the international public telegram service | F.1-F.19    |
+| The gentex network                                              | F.20-F.29   |
+| Message switching                                               | F.30-F.39   |
+| The international telemessage service                           | F.40-F.58   |
+| The international telex service                                 | F.59-F.89   |
+| Statistics and publications on international telegraph services | F.90-F.99   |
+| Scheduled and leased communication services                     | F.100-F.104 |
+| Phototelegraph service                                          | F.105-F.109 |
+
+## **MOBILE SERVICE**
+
+|                                                        |             |
+|--------------------------------------------------------|-------------|
+| Mobile services and multdestination satellite services | F.110-F.159 |
+|--------------------------------------------------------|-------------|
+
+## **TELEMATIC SERVICES**
+
+|                                           |             |
+|-------------------------------------------|-------------|
+| Public facsimile service                  | F.160-F.199 |
+| Teletex service                           | F.200-F.299 |
+| Videotex service                          | F.300-F.349 |
+| General provisions for telematic services | F.350-F.399 |
+
+## **MESSAGE HANDLING SERVICES**
+
+F.400-F.499
+
+## **DIRECTORY SERVICES**
+
+F.500-F.549
+
+## **DOCUMENT COMMUNICATION**
+
+|                                      |             |
+|--------------------------------------|-------------|
+| Document communication               | F.550-F.579 |
+| Programming communication interfaces | F.580-F.599 |
+
+## **DATA TRANSMISSION SERVICES**
+
+F.600-F.699
+
+## **AUDIOVISUAL SERVICES**
+
+**F.700-F.799**
+
+## **ISDN SERVICES**
+
+F.800-F.849
+
+## **UNIVERSAL PERSONAL TELECOMMUNICATION**
+
+F.850-F.899
+
+## **HUMAN FACTORS**
+
+F.900-F.999
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **Service description and requirements for multimedia conference services over IP networks**
+
+## **Summary**
+
+The purpose of this Recommendation is to define the multimedia conference services based on IP networks. The service provides real-time communication between several users in different locations over an IP network. The service description, functional model, application scenarios and requirements of the IP multimedia conference services are provided. The IP multimedia conference service is one class of the generic services identified in ITU-T Rec. F.702, and its description follows the methodology described in ITU-T Rec. F.701. The requirements for the IP multimedia conference services are derived from the scenarios for different applications the said services can support. Therefore, the services requirements accommodate the demands of different kinds of users and assist in enabling intercommunications between the services systems provided by different telecom operators, or between the equipment manufactured by different manufacturers.
+
+###### **Source**
+
+ITU-T Recommendation F.733 was approved on 13 September 2005 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure.
+
+# FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 2005
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+# CONTENTS
+
+###### Page
+
+|     |                                                  |    |
+|-----|--------------------------------------------------|----|
+| 1   | Scope .....                                      | 1  |
+| 2   | References.....                                  | 1  |
+| 2.1 | Normative references.....                        | 1  |
+| 2.2 | Informative references.....                      | 1  |
+| 3   | Definitions .....                                | 1  |
+| 4   | Convention.....                                  | 2  |
+| 5   | Prose description.....                           | 2  |
+| 6   | Application functional model .....               | 3  |
+| 6.1 | Functional model .....                           | 3  |
+| 6.2 | Multimedia conference mode .....                 | 4  |
+| 6.3 | User roles.....                                  | 4  |
+| 7   | Scenarios.....                                   | 5  |
+| 7.1 | Multimedia interactive conference .....          | 5  |
+| 7.2 | Multicast conference .....                       | 7  |
+| 7.3 | Mixed mode conference .....                      | 7  |
+| 8   | Requirements of IP multimedia conference .....   | 8  |
+| 8.1 | User requirements.....                           | 8  |
+| 8.2 | Application requirements .....                   | 9  |
+| 8.3 | Numbering requirements .....                     | 9  |
+| 8.4 | Security requirements.....                       | 9  |
+| 8.5 | Authentication and accounting requirements ..... | 10 |
+| 8.6 | QoS requirements .....                           | 10 |
+| 9   | Interworking and intercommunication .....        | 10 |
+| 9.1 | Terminals with different capabilities.....       | 10 |
+| 9.2 | Terminals in different networks .....            | 10 |
+| 9.3 | Different IP multimedia conference systems ..... | 11 |
+
+
+
+# Service description and requirements for multimedia conference services over IP networks
+
+# 1 Scope
+
+This Recommendation describes the multimedia conference service system over IP networks, its application scenarios and service requirements.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+## 2.1 Normative references
+
+None.
+
+## 2.2 Informative references
+
+- ITU-T Recommendation F.700 (2000), *Framework Recommendation for multimedia services*.
+- ITU-T Recommendation F.701 (2000), *Guideline Recommendation for identifying multimedia service requirements*.
+- ITU-T Recommendation F.702 (1996), *Multimedia conference services*.
+- ITU-T H-Series Recommendations – Supplement 1 (1999), *Application profile – Sign language and lip-reading real-time conversation using low bit-rate video communication*.
+
+# 3 Definitions
+
+This Recommendation defines the following terms:
+
+**3.1 chairman:** the user who chairs the meeting and manages the conference.
+
+**3.2 communication mode:** a communication mode is defined by the various channels supporting the media used for the conference. Changes in communication mode may occur during the course of the conference, in order to set up or eliminate one of the media, or to change its quality level and thus the bit-rate allocation. The mode change may be used for instance to temporarily add a channel for transmitting still pictures.
+
+**3.3 conference convener:** The user who has organized the conference.
+
+**3.4 centralized multipoint conference:** A centralized multipoint conference is one in which all participating terminals communicate in a point-to-point fashion with special control or processing facilities.
+
+**3.5 decentralized multipoint conference:** A decentralized multipoint conference is one in which the participating terminals multicast their audio, video and text to all other participating terminals.
+
+**3.6 IP multimedia conference service:** A type of multimedia conference service based on IP network that utilizes networks for control and media transfer.
+
+**3.7 multicast conference:** A multicast conference is one in which there is one transmitter of media streams and many receivers. There is no bidirectional transmission of control or media streams. Such conferences may be implemented using network transport multicast facilities, if available.
+
+**3.8 multipoint interactive conference:** A multipoint interactive conference is one in which all participants are transmitters and receivers. There is bidirectional transmission of control or media streams. Such conferences should be implemented using special control or processing facilities, if available.
+
+**3.9 multimedia conference service:** A multimedia conference service provides real-time transmission of voice together with motion video, real time text and/or various types of multimedia information between groups of users in two or more locations.
+
+**3.10 muting:** Preventing sound to be transmitted from a terminal equipment.
+
+**3.11 presenter:** The participant in a conference who controls the visual information being actively discussed.
+
+# 4 Convention
+
+In this Recommendation the following conventions are used:
+
+- "shall" indicates a mandatory requirement.
+- "should" indicates a suggested but optional course of action.
+- "may" indicates an optional course of action rather than a recommendation that something take place.
+
+# 5 Prose description
+
+An IP multimedia conference system provides real-time communication between several users in different locations, combining the audio, video and real-time text information of the participants, and other multimedia information if needed.
+
+The service can be bidirectional, and provide for interconnection of two or more multimedia conference terminals on an equal basis; it can also be unidirectional, where part of the terminals can only receive, while others can only send. If there are two or more terminals in the conference, equipment that can provide multimedia information control and exchange is needed. Network side equipment that can manage and control the conference, and provide authentication and billing is also necessary.
+
+The multimedia conference services may be provided after prior arrangement with a service provider, or they may be generally available. The conference connection can be established by a user or by a management system.
+
+The location of a multimedia conference participant could be anywhere where the network is accessible, e.g., meeting room, office, home, or even on the highway. The participants take part in the meeting by means of a multimedia conference terminal. The terminals may access the network by wire or wireless means. There are three types of terminal:
+
+- Hardware-based terminals, which include two sub-types of terminal:
+  - a) Special conference terminals for studios dedicated to and equipped for multimedia conferences;
+  - b) Portable terminals which are only used on a part-time basis for teleconferencing and which can be moved from one place to another.
+
+- Software-based terminals running on computers.
+- Other types of terminals, e.g., POTS terminals, could also be used in the conference. Although there are certain limitations regarding their capability to send and receive different types of information used in a multimedia conference call, they are at least able to exchange speech, allowing their users to take part in the discussion.
+
+# 6 Application functional model
+
+## 6.1 Functional model
+
+![Figure 1/F.733 – The multimedia conference functional model. The diagram shows the functional architecture of a multimedia conference system. At the top, an 'AAA' (Authentication, Authorization, Accounting) block is connected to a 'Conference management & control' block via a thick double-headed arrow (AAA information streams). The 'Conference management & control' block is connected to a 'Voice/video/data switch & process' block via a dashed double-headed arrow (Conference management & control information streams). Below the 'Conference management & control' block, a 'user' block is connected via a dash-dot double-headed arrow (User's conference management message). The 'user' block is also connected to an 'IP multimedia conference terminal' block via a dashed double-headed arrow. The 'IP multimedia conference terminal' block is connected to a 'Voice/video/data switch & process' block via a solid double-headed arrow (Multimedia information streams). The 'Voice/video/data switch & process' block is connected to an 'interworking' block via a thick double-headed arrow. The 'interworking' block is connected to an 'Other multimedia conference terminal' block via a thick double-headed arrow. A horizontal dashed line labeled 'IP-based network' separates the network functions (above the line) from the user functions (below the line). A label 'a' is placed near the 'interworking' block. A legend at the bottom left defines the line types: solid for Multimedia information streams, dashed for Conference management & control information streams, dash-dot for User's conference management message, and thick for AAA information streams. The label 'F.733_F01' is in the bottom right corner.](b3baf3a29b67c7425d2562ddbc52f0cc_img.jpg)
+
+Figure 1/F.733 – The multimedia conference functional model. The diagram shows the functional architecture of a multimedia conference system. At the top, an 'AAA' (Authentication, Authorization, Accounting) block is connected to a 'Conference management & control' block via a thick double-headed arrow (AAA information streams). The 'Conference management & control' block is connected to a 'Voice/video/data switch & process' block via a dashed double-headed arrow (Conference management & control information streams). Below the 'Conference management & control' block, a 'user' block is connected via a dash-dot double-headed arrow (User's conference management message). The 'user' block is also connected to an 'IP multimedia conference terminal' block via a dashed double-headed arrow. The 'IP multimedia conference terminal' block is connected to a 'Voice/video/data switch & process' block via a solid double-headed arrow (Multimedia information streams). The 'Voice/video/data switch & process' block is connected to an 'interworking' block via a thick double-headed arrow. The 'interworking' block is connected to an 'Other multimedia conference terminal' block via a thick double-headed arrow. A horizontal dashed line labeled 'IP-based network' separates the network functions (above the line) from the user functions (below the line). A label 'a' is placed near the 'interworking' block. A legend at the bottom left defines the line types: solid for Multimedia information streams, dashed for Conference management & control information streams, dash-dot for User's conference management message, and thick for AAA information streams. The label 'F.733\_F01' is in the bottom right corner.
+
+**Figure 1/F.733 – The multimedia conference functional model**
+
+The IP multimedia conference functional model is shown in Figure 1. Multimedia conference terminals can access IP-based networks with several kinds of modes, e.g., LAN, WLAN, xDSL, PLMN, and PSTN.
+
+Network functions above the dashed line constitute an IP multimedia conference service platform directly related with users:
+
+- a) Conference Management and Control Function: it can initiate an immediate conference according to the user's demand, or accept the user's conference reservation and allocate the system resource.
+- b) Multimedia Switch and Process Function: it provides control functions to the conference, switches and processes the audio, video and text, and/or data streams.
+- c) Interworking function: other multimedia conference terminals can access the IP multimedia conference network via the interworking function.
+- d) Authentication, Authorization and Accounting (AAA): it provides the Conference Management and Control Function with the user's identification information, and processes accounting information from the Conference Management and Control Function.
+
+## 6.2 Multimedia conference mode
+
+Two types of basic multimedia conferences service modes are addressed in this Recommendation. Other types are left to the creativity of the service providers and equipment manufacturers.
+
+### a) *Multipoint interactive conference mode*
+
+In this mode, all participating terminals communicate in a point-to-point fashion, possibly with the involvement of the Multimedia Switch & Process Function. The centralized multipoint conference, and the decentralized multipoint conference are two examples.
+
+### b) *Multicast conference mode*
+
+In this mode, only one terminal in the conference transfers local multimedia information streams to the Multimedia Switch & Process Function, but does not receive them. Other terminals in the conference only receive the information from Multimedia Switch & Process Function but do not transfer information themselves.
+
+## 6.3 User roles
+
+According to their different roles in the conference, users can be identified as a Conference Controller, Conference Chairman and Conference Participant.
+
+A Conference Convener can initiate a conference on demand or reserve a conference. The conference convener is also the conference controller. The accounting information is bound to the role of Conference Convener. The role of Conference Controller can be moved to another user or terminal. The basic<sup>1</sup> functions include:
+
+- a) Reserving a conference;
+- b) Cancelling/modifying the reservation;
+- c) Initiating a conference on demand;
+- d) Terminating the conference;
+- e) Inviting a new participant;
+- f) Accepting a new participant;
+- g) Disconnecting a participant from the conference.
+
+Controller's advanced<sup>1</sup> functions include:
+
+- a) Splitting the conference;
+- b) Extending the conference.
+
+During a conference, a participant can apply to be chairman. A chairman is responsible for its management. Basic functions are:
+
+- a) Managing the conference;
+- b) Displaying him or herself, or one of the other participants, on the terminal screens.
+
+The chairman's advanced functions include:
+
+- a) Giving the floor to a participant;
+- b) Ensuring the conference terminals broadcast in turn;
+- c) Muting another terminal;
+- d) Organizing or allowing a private conversation;
+
+---
+
+<sup>1</sup> In this Recommendation, "basic" refers to a mandatory requirement, while "advanced" refers to a suggested but optional feature or procedure.
+
+- e) Controlling data transfer;
+- f) Controlling remote equipment.
+
+The conference participant's basic functions include:
+
+- a) Participation in the conference;
+- b) Muting local microphones.
+
+The conference participant's advanced functions include:
+
+- a) Requesting to be nominated as chairman;
+- b) Requesting the floor;
+- c) Receiving certain indicative information, such as site and time;
+- d) Initiating a data conference, such as remote collaboration and transferring of files;
+- e) Recording the conference.
+
+# **7 Scenarios**
+
+This clause describes typical service scenarios illustrating the multimedia conference service and deriving its service requirements.
+
+## **7.1 Multimedia interactive conference**
+
+### **7.1.1 Formal conference**
+
+TTP is a big international company. Annually, a highly formal conference is held to sum up the year's work on the 10th December. S is the CEO of the company who makes a report on all aspects of the company to the board of directors. The directorate consists of 5 members. Generally, these directors are located in different locations. Their offices are equipped with special conference terminals. Usually, the year-end reporting conference progresses in the following way:
+
+Step 1: Reserve the conference. Conventionally, the CEO's secretary submits information such as the starting time, the duration of the conference, participants, the bandwidth, codec and text requirement to the multimedia conferencing system in advance. Since this conference is very formal, the bandwidth is set to the largest value that the system supports, in order to achieve a high resolution of images.
+
+Step 2: As the scheduled time approaches, the conferencing system calls each reserved terminal. S's secretary, together with the other six formal participants, participates in the conference to log the conference. He may only listen but may not take the floor. There is also a typing interpreter booked for the meeting because C has a hearing impairment and needs to have simultaneous text support to be sure he perceives everything correctly. When the conference is established, director A applies to be the chairman, and then begins to moderate the conference.
+
+Step 3: The chairman lets the CEO of the company speak. S has organized the contents into PPT formats. When he begins to report, all participants' screens are divided into two parts. The PPT is on the background while a movable window is displaying S who is speaking on the foreground. The chairman thinks that the picture is not clear enough, nor the voice loud enough. He then adjusts S's camera and the microphone to ensure everyone sees and hears S clearly. The typed interpretation of the speaker appears in a text window directly under the video image.
+
+Step 4: Director B is confused by a figure in the presentation. He then presses the floor key. When A receives the request, he notifies S to pause, and lets B speak. Then all participants, except B, can see B, while B sees his previous speaker's picture, that is, the picture of S. When B finishes speaking, S takes the floor again. S then answers the question and sends the related report forms to other participants to make the problem clear.
+
+Step 5: The typing interpreter listens in on the conference and types on a chord keyboard at normal talking speed. C can perceive the conference very well by combining the hearing, the good quality, smooth video that provides the possibility for lip reading, and the types interpretation. C asks to make a short comment and the chairman gives him the floor to make an important comment from his long experience in the company.
+
+Step 6: Since S's speech is longer than planned, the reserved time will soon run out after the discussion. The chairman extends the conference by half an hour. When S finishes speaking, the chairman changes the conference to voice control mode. Text control mode may be also supported. The person who takes floor is displayed on the screens of other participants. But the participants feel uncomfortable with this mode, so the chairman applies six sub-pictures. The participants can then see each other.
+
+Step 7: After the discussion, the chairman begins to make a summary. The video is changed to display the chairman only. A praises the company's achievement, and points out what should be improved. Then A cancels his chairmanship, and they chat at random.
+
+Step 8: The conference is over. The participants say good-bye to each other. The conference is terminated automatically after everyone has left.
+
+Step 9: After the conference, the typed interpretation is kept for the secretary who will draw up the formal minutes of the meeting.
+
+### **7.1.2 Discussion conference**
+
+While the year-end conference is in progress, the engineers of the company, located in different places, are discussing their new product via the multimedia conference system. They use portable desktop terminals. The conference progresses in the following way:
+
+Step 1: John is in charge of the new product. Since he is going to introduce the new product, he uses the special conference terminal located in the assembly room, whose performance is better than others. First, he calls the other twenty engineers named B, C, D, E, etc., who are in charge of the different aspects of the product. Each engineer has a terminal. Due to the capability restriction of the other desktop terminals, the bandwidth is lower. The resolution of the picture is not as high as on John's special conference terminal, but the picture is still clear enough.
+
+Step 2: John introduces the product to others, and shows the sample. Because the other twenty terminals could not display all the details of the product, John transfers some photos to show details more clearly.
+
+Step 3: The discussion begins after John has finished his introduction. The meeting is then split into four sub-conferences. All sub-conferences use voice control mode so the participants can speak freely and at the same time send text or graphics.
+
+Step 4: Fifteen minutes later, the discussion is finished. The four sub-conferences are combined into one conference. The majority of the participants agree that the initial requirement for the new product has been accomplished, and put forward some suggestions for what should be improved. However, engineer C considers that they should hear the suggestions of the marketing people. John, as the convener of the conference, then invites two marketing people named Aa and Bb to join the discussion. Aa and Bb accept the invitation.
+
+Step 5: Aa and Bb ask various questions and receive the relevant information. They put forward their suggestions on the marketing aspect and leave. John sums up all the suggestions and compiles a file. All participants modify this file with the file coordination function. John then makes plans for the next step according to the final file.
+
+Step 6: John announces the conference is over. After John leaves, the conference is terminated.
+
+### 7.1.3 Family chatting
+
+John goes back home after a full day work. He decides to call his parents to discuss the New Year holiday plan.
+
+Step 1: John initiates a videophone call to his parents. The call rate is not high considering the terminal's capability and cost. Although the image resolution is low, they can still see each other clearly. A small text window is visible below the video, for the real-time text component.
+
+Step 2: After exchanging conventional greetings, they begin to talk about the plan for the coming holiday. John's daughter Sasa calls John during their discussion. John tells Sasa that he is talking about their holiday plan with her grandparents, and Sasa asks to join in the discussion. Sasa joins the call after John's parents have agreed. Since Sasa is using a mobile terminal, she chooses to receive the call in the "voice only" mode.
+
+Step 3: John's father had a stroke a couple of years ago. It affected his speech. So, when he wants to contribute to the discussion, he types in the text area and the text appears nearly character-by-character on the participants' terminals. All appreciate sharing his experience of an earlier trip to China and his hints on the wonderful nature trips to be made in the Sichuan and Tibet areas.
+
+Step 4: The result to the New Year's plan discussion is that John's family will travel to China, and back to the house of their grandparents, the day before Christmas Day, for a party. John then invites his sister Lindy to join the conference call because she is in China on business. They have not seen each other for a long time, so John asks the system to change the picture mode. Sasa joins the conference with audiographics-only mode (audio plus still-image and graphics).
+
+Step 5: When they talk about the travel issue, Lindy announces that she has taken many photos in China. She then shows these pictures, together with text annotation, to the others. All the terminals display Lindy's photos. They continue their discussion based on these pictures. Finally, they decide that the destinations of the trip shall be Beijing and Tibet. John types a link to a travel information site where they can all get information to continue their planning after the call.
+
+Step 6: After the holiday arrangement is decided, John ends the family discussion.
+
+## 7.2 Multicast conference
+
+The following is an education scenario.
+
+In order to increase the whole corporation's ability to face increasing market competition, TTP's management department decides to give a market education seminar to the department managers. A famous marketing expert is responsible for the seminar. The expert is very busy so he makes a videodisc on the seminar. The organizer holds a multicasting meeting for the educational seminar.
+
+Step 1: Before the seminar begins, the educational organizer calls all the managers;
+
+Step 2: The organizer plays the videodisc. The audience, each located in his/her own office, receives the educational seminar;
+
+Step 3: The meeting is terminated after the videodisc is over.
+
+## 7.3 Mixed mode conference
+
+The following scenario is on a new product release situation.
+
+After the discussion on the TTP's new product, several modifications have been made. John who is responsible for the new product has decided it can be now released. Several means are used to release the new product. There are four target groups for the product release. The members of the first group are the relevant persons inside the company. Those from the second group are the major customers of the company. Those from the third group are the customers who registered by Internet after receiving advertisements of the product's release. Those from the fourth group are anonymous
+
+customers who watch the product release via Internet multicast. The first two classes of customers have full privileges to participate in the conference. The third class of customers can take the floor with the chairman's permission. The last class of customers can only observe, but they can leave messages on the bulletin board system.
+
+Step 1: Before the product is released, John calls all who comprise the first three classes of customers, and begins the broadcast through the Internet.
+
+Step 2: At the beginning, John shows and introduces the new product to everyone and makes a detailed presentation. During this procedure, John answers some questions from the second class of customers.
+
+Step 3: After the product presentation is completed, John answers questions from the third class of customers and replies to the messages on the bulletin board from the fourth class of customers.
+
+Step 4: The product release presentation is very successful. Both the major customers and the registered customers are satisfied with the product and the release presentation. A month later, John's colleague David retrieves and replays John's product release from the storage system and derives many good ideas for his own product release from it.
+
+# **8 Requirements of IP multimedia conference**
+
+## **8.1 User requirements**
+
+Basic requirements:
+
+- The user can initiate a multipoint conference on demand, or reserve a conference in several ways. For example, the user can reserve a conference or initiate an instant conference from the terminal, or login the conference management server and submit the conference information, or call the service provider operator;
+- Interactive audio, video and text in real-time, clear and smooth voice and video;
+- Users can access a multimedia conference from anywhere, if necessary;
+- Users can participate in the conference in different roles: convener (controller), chairman, participant, auditors and anonymous participants.
+
+Advanced requirements:
+
+- Users can request conference prolongation and conference termination ahead of the scheduled termination time during the conference;
+- Multi-subpictures can be displayed on the terminal's screen, and terminals can distribute multiple videos to display on several screens;
+- Terminals can join a multimedia conference with different codecs and different rates;
+- Data transfer function should be supported, e.g., document sharing, coordination, electronic white bulletin and slide demo etc., can be used;
+- Users can control remote terminals, such as the camera, microphone, etc.;
+- Conference can be multicast according to the controller's demand;
+- One conference can be split into several subconferences, and each subconference can be held as an individual conference under the control of the controller;
+- New participants can join or be invited into the ongoing conference, and each terminal may be disconnected from the conference at any time;
+- The means to participate in the conference and to handle the terminals and services can be provided to people with disabilities;
+- Users can retrieve and replay the archived conference.
+
+## 8.2 Application requirements
+
+Basic requirements:
+
+- Reserved conference and conference on-demand can be held automatically according to the user's requests;
+- Voice, video and text streams can be exchanged and processed, and QoS guarantee should be provided;
+- Various access methods are allowed, such as xDSL, Ethernet, WLAN, GSM, and 3G;
+- Different roles of the participants and different conference control modes are supported including voice control mode, chairman control mode, and text control mode, etc.
+
+Advanced requirements:
+
+- The system can schedule and manage conference resources automatically;
+- One or more streaming channels can be provided, and can be set up on demand;
+- The multimedia conference network can handle different codecs and different rates in one conference;
+- Remote device control should be supported;
+- Data transmission is supported, such as real-time text, document sharing, cooperation, bulletin board and slide demo;
+- The system can broadcast to one of the conference terminals according to the conference controller's request;
+- The system can support splitting a conference into several subconferences according to the conference controller's request;
+- The system can disconnect or invite terminals at any time, if necessary;
+- The conference can be archived, researched and reviewed.
+
+## 8.3 Numbering requirements
+
+To authorize a user, he/she should be assigned a unique identification number accompanied by other necessary information. The number should be used as the destination indication when the user is called, and as the identification for accounting. It should support the mobility of user terminals when necessary.
+
+## 8.4 Security requirements
+
+The security of a multimedia conference should be ensured: different security levels may be provided according to the user requirement. There are three classes of security:
+
+- a) user authentication and access security;
+- b) call security;
+- c) media stream encryption.
+
+When convening a conference with security, the following contents should be included:
+
+- 1) The convener should designate whether the meeting is security-supported or not when reserving a meeting, and the level of security should also be designated;
+- 2) For the conference on-demand, the security requirement and its level should also be submitted.
+
+## **8.5 Authentication and accounting requirements**
+
+The system should accept the authorized user's access to a multimedia conference network, and provide authorized application to the user.
+
+The system should not only collect and transfer accounting data of the multimedia conference service user accurately, but also provide multiple, alternative-accounting modes for different application scenarios.
+
+## **8.6 QoS requirements**
+
+Time delay, jitter and packets loss due to the IP network are the main effects to QoS. The network and terminal equipment for the multimedia conference service should be capable of real-time multimedia information processing, and of maintaining clarity and smoothness of the voice, moving picture and real-time text. The equipment should also be able to receive and process other data formats properly.
+
+# **9 Interworking and intercommunication**
+
+Three types of interworking or intercommunication may be related to the IP multimedia conference service:
+
+- interworking and intercommunication between terminals with different capabilities;
+- interworking and intercommunication between terminals in different networks (PSTN, ISDN, etc.);
+- interworking and intercommunication between different IP multimedia conference systems.
+
+## **9.1 Terminals with different capabilities**
+
+Terminals with different characteristics and capabilities may be connected in a multimedia conference. Three ways of interworking or intercommunication may then be provided:
+
+- use of a common mode which every terminal in the call can handle; this will decrease the quality and functionalities to those of the terminal with the lowest quality level for each media component; however, communication is always possible because all terminals have at least the basic audio capability;
+- use of their normal mode for the terminals supporting higher quality levels, with partial functionalities only for the terminals with lower quality levels, which are thus given a secondary status; for instance, some terminals may have audio and video while others may have audio capability only; it may also happen that terminals have different and incompatible data capabilities, and thus cannot be used;
+- transcoding and rate matching in the media exchange and process so that each terminal receives and transmits the signals it is able to handle.
+
+## **9.2 Terminals in different networks**
+
+The multimedia conference system should accept terminals in different networks (for example, visual telephone terminals over ISDN, visual telephone terminals over GSTN, Visual telephone terminals over mobile radio). That means that, when different terminals access, the multimedia system supports the network protocol translation. The requirements for this type of interoperation are:
+
+- audio format and code conversion;
+- video format and code conversion;
+- text format conversion;
+- data protocol conversion;
+
+- bit stream conversion;
+- call control signalling conversion.
+
+## **9.3 Different IP multimedia conference systems**
+
+There are many IP multimedia conference systems now available. Intercommunication is needed if the terminals are located in different service systems. The requirements for this type of intercommunication should support:
+
+- authentication between different systems;
+- system security;
+- shared system resources;
+- accounting between different systems.
+
+
+
+
+
+# SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                             |
+|-----------------|---------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                           |
+| Series D        | General tariff principles                                                                   |
+| Series E        | Overall network operation, telephone service, service operation and human factors           |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                             |
+| Series G        | Transmission systems and media, digital systems and networks                                |
+| Series H        | Audiovisual and multimedia systems                                                          |
+| Series I        | Integrated services digital network                                                         |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals |
+| Series K        | Protection against interference                                                             |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant     |
+| Series M        | Telecommunication management, including TMN and network maintenance                         |
+| Series N        | Maintenance: international sound programme and television transmission circuits             |
+| Series O        | Specifications of measuring equipment                                                       |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                |
+| Series Q        | Switching and signalling                                                                    |
+| Series R        | Telegraph transmission                                                                      |
+| Series S        | Telegraph services terminal equipment                                                       |
+| Series T        | Terminals for telematic services                                                            |
+| Series U        | Telegraph switching                                                                         |
+| Series V        | Data communication over the telephone network                                               |
+| Series X        | Data networks, open system communications and security                                      |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks   |
+| Series Z        | Languages and general software aspects for telecommunication systems                        |

marked/F/T-REC-F.740-199308-I_PDF-E/raw.md

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+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.740**
+
+(08/93)
+
+**OPERATIONS AND QUALITY OF SERVICE  
+AUDIOVISUAL SERVICE**
+
+---
+
+**AUDIOVISUAL INTERACTIVE SERVICES**
+
+**ITU-T Recommendation F.740**
+
+(Previously "CCITT Recommendation")
+
+---
+
+# FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation F.740 was prepared by ITU-T Study Group 1 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 31st of August 1993.
+
+---
+
+# NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# CONTENTS
+
+|                                                          | <i>Page</i> |
+|----------------------------------------------------------|-------------|
+| 1 Introduction .....                                     | 1           |
+| 2 Definition of the AVI Service .....                    | 1           |
+| 3 Description of the AVI Service .....                   | 2           |
+| 3.1 AVI general aspects .....                            | 2           |
+| 3.2 The main roles .....                                 | 2           |
+| 3.3 Their functional needs .....                         | 2           |
+| 3.4 Terminal aspects .....                               | 4           |
+| 3.5 Terms and definitions .....                          | 4           |
+| 4 Procedures .....                                       | 5           |
+| 5 Charging principles .....                              | 5           |
+| 5.1 General .....                                        | 5           |
+| 5.2 Networks capabilities for charging .....             | 6           |
+| 6 Quality of service .....                               | 6           |
+| 6.1 Network optimization .....                           | 6           |
+| 6.2 Media quality .....                                  | 6           |
+| 6.3 Security .....                                       | 6           |
+| 7 Interworking and intercommunication requirements ..... | 6           |
+| Annex A – Examples of multimedia application.....        | 7           |
+
+
+
+# **AUDIOVISUAL INTERACTIVE SERVICES**
+
+*(Geneva, 1993)*
+
+The ITU-T,
+
+*considering*
+
+- (a) the existing (draft) documents on Audiovisual Interactive systems and protocols in SG 8;
+- (b) the state of the art of standardization of multimedia and hypermedia information in ISO;
+- (c) the need for handling audiovisual information of various types, namely text, graphics, still images and moving pictures on telecommunication networks;
+- (d) the need of having this audiovisual information shared by a various range of users supplying, managing or retrieving applications controlling it, and thus, using a wide and complex range of functions;
+- (e) that users are justified to demand an acceptable minimum quality of service;
+- (f) the current setting up of both pilot and operational AVI Services in the fields of education, marketing help, entertainment, etc.,
+
+*adopts*
+
+the subsequent Recommendation dealing with the General Description for Audiovisual Interactive Service (AVIS).
+
+# **1 Introduction**
+
+The purpose of this Recommendation is to define and describe, from the user's point of view, the general features and attributes of the AVI Service, regardless of the network environment where the service might be provided.
+
+# **2 Definition of the AVI Service**
+
+An AVI Service is a service which provides, through appropriate access by standardized procedures, users of terminals or workstations with information which consists of various input and output presentation elements, possibly combined, such as:
+
+- texts;
+- graphics;
+- pictures;
+- audio sequences;
+- video sequences.
+
+A range of functions may be supplied to the user such as:
+
+- simple retrieval;
+- interactive consultation;
+- re-arrangement of the assembling of elements;
+- modification of the elements themselves.
+
+The AVI Service also covers other service aspects related to the creation and management of the information.
+
+It is considered that the operation requires the participation of a number of organizations. The whole set of functionalities offered by the AVI Service is usually carried out via telecommunications networks.
+
+The AVI Service is essentially an asymmetrical service in which a single service provider is providing the service to several users. Additionally, rerouting from one service provider to another one may be offered.
+
+The users of an AVI Service may be equipped with an heterogeneous set of terminals or workstations.
+
+# 3 Description of the AVI Service
+
+### 3.1 AVI general aspects
+
+Several types of users will be allowed to access the AVI Service. Different rights should be given to them. As an example, an author will need to make use of enhanced functions given by his AVI terminal operating system and allowing him the access to remote systems when necessary via telecommunication networks whereas a simple retriever will remain more passive and simply need to consult the contents proposed by the AVI application.
+
+The information life cycle varies according to the type of application and can have different values on a scale from short to long.
+
+Three entities need to exchange information. Therefore, to set up an AVI application, telecommunications will be used.
+
+### 3.2 The main roles
+
+The AVI Service provides with facilities to fulfil the requirements of the users involved in creating, exchanging, modifying, managing and executing AVI applications.
+
+The users of the AVI Service may have several roles:
+
+- author;
+- information manager;
+- preparer;
+- retriever,
+
+dealing with the following families of functions:
+
+- editing functions;
+- information management functions;
+- execution and retrieval functions.
+
+According to the users' needs, various and numerous exchanges will be set up between systems or subsystems providing with the functions.
+
+An AVI Service can be illustrated as in the Figure:
+
+![Diagram of an AVI service architecture showing roles and functions.](e23c9577e177bf077bac8951a775dd90_img.jpg)
+
+The diagram illustrates the architecture of an AVI service. It features a central 'Information Management' block. Above this block is the 'Information Manager' role, connected by a vertical line. To the left is the 'Author' role, connected by a horizontal line. To the right are the 'Preparer' and 'Retriever' roles, also connected by horizontal lines. Inside the 'Information Management' block, there are three sub-functions: 'Editing', 'Execution', and 'Exchange'. 'Editing' and 'Execution' are at the bottom, connected by a horizontal double-headed arrow. 'Exchange' is at the top, with arrows pointing to it from both 'Editing' and 'Execution'. The entire diagram is enclosed in a grey rectangular background.
+
+Diagram of an AVI service architecture showing roles and functions.
+
+T0102510-92/d01
+
+FIGURE 1/F.740  
+An AVI service
+
+### 3.3 Their functional needs
+
+Each of the various roles has specific functional requirements with regards to the first three families of functions identified i.e. editing, information management, execution.
+
+As the respective locations of entities assuring roles and systems supplying functions may be distant, exchange functions should be activated as well.
+
+Table 1 hereafter, breaks down the needs of the four categories of roles according to the three families of functions.
+
+TABLE 1/F.740
+
+#### **Roles versus functional requirements**
+
+| Functions           |                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                      |
+|---------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Roles               | Editing                                                                                                                                                                                                                                                                                                          | Information Management                                                                                                                                                                                                                                                                                                                         | Execution                                                                                                                                                                                            |
+| Author              | <ul style="list-style-type: none"> <li>– AVI creation or updating</li> <li>– Creation of the catalogue for AVIs already edited</li> <li>– Modification of AVIs already edited</li> <li>– Validation and transmission to information management system</li> <li>– Concatenation of AVIs already edited</li> </ul> | <ul style="list-style-type: none"> <li>– Management of edited AVIs and updates</li> <li>– Usage follow-up, trace processing</li> <li>– Statistics and payment</li> </ul>                                                                                                                                                                       | <ul style="list-style-type: none"> <li>– Debugging of AVIs</li> <li>– Experimentation using a sample user group</li> </ul>                                                                           |
+| Information Manager | <ul style="list-style-type: none"> <li>– Consultation of catalogues of AVIs already edited</li> <li>– Transmission to information management of AVIs already edited or their updates</li> </ul>                                                                                                                  | <ul style="list-style-type: none"> <li>– Creation and maintenance of catalogue for AVIs ready for management</li> <li>– Storage of AVIs and updates</li> <li>– Implementation of a pricing policy</li> <li>– Delivery management (profile verification)</li> <li>– Retriever and preparer management (access control, billing, ...)</li> </ul> | <ul style="list-style-type: none"> <li>– Collection of execution traces and recovery context</li> </ul>                                                                                              |
+| Preparer            |                                                                                                                                                                                                                                                                                                                  | <ul style="list-style-type: none"> <li>– Choice of AVIs already managed</li> <li>– Negotiation of configuration, parameters and installation on real supports as required</li> <li>– Sending of retriever usage follow-up</li> </ul>                                                                                                           | <ul style="list-style-type: none"> <li>– Reception and installation of AVIs and updates</li> <li>– Verification of correct installation</li> <li>– Collection of traces generated by AVIs</li> </ul> |
+| Retriever           |                                                                                                                                                                                                                                                                                                                  | <ul style="list-style-type: none"> <li>– Choice of AVIs already managed</li> <li>– Usage follow-up</li> <li>– Recovery management</li> </ul>                                                                                                                                                                                                   | <ul style="list-style-type: none"> <li>– Choice of AVIs already installed</li> <li>– Recovery management (Note)</li> <li>– AVI usage</li> </ul>                                                      |
+
+NOTE – A retriever may recover an AVI, later after its interruption, in the same context of usage.  
+Two concrete examples of AVI applications are given in Annex A.
+
+### 3.4 Terminal aspects
+
+Terminal equipment needs to provide with a set of functions such as:
+
+- display of text, graphics, still images preferably in colour and optionally moving images;
+- reproduction of sound;
+- acquisition of user interactions.
+
+All these functions should make use of appropriate standards defined or being defined in ISO IEC/JTC 1 and ITU-T.
+
+Terminals will be connected to appropriate networks by making use of interfaces and protocols defined in ITU-T.
+
+Terminals are equipped with a minimum set of items, namely a keypad, mouse, monitor and loudspeaker.
+
+### 3.5 Terms and definitions
+
+#### 3.5.1 Specific terminology
+
+For the purpose of this Recommendation, the following definitions apply:
+
+**role:** The role is either a person who activates, or a process which has been designed by a person in order to activate a functionality of an AVI application.
+
+**retriever:** The role who mainly consults the application by interacting with the presentation process.
+
+**preparer:** The role who mainly selects, installs, personalizes and concatenates the applications as well as following up their execution.
+
+**information manager:** The role who mainly defines or modifies user access authorization and tariffing, then provides the execution process with the applications to be executed or their updates.
+
+**author:** The role who mainly creates and validates applications or updates and supplies them to the information manager for their distribution.
+
+**editing:** Creation of applications, including design, use of media, development, verification, modification, updating and validation before the applications become available to the users.
+
+**information management:** Application management, including storage, classification, catalogue creation and management, retriever and preparer management, tariffication, monitoring usage processing, context recovery management, etc.
+
+**execution:** Application usage after installation, user interface management, monitoring usage implementation and, where appropriate, upstream connection with an information management system or directly with an editing system in case of an implementation in progress.
+
+**AVI application:** An AVI application is a dedicated use of the AVI Service to satisfy a particular requirement. An AVI application contains at least structural and presentation elements.
+
+The presentation elements are either input or output objects of various nature. They may be of monomedia, multimedia or hypermedia type.
+
+The execution of an AVI application consists in activating scriptware transferred as part of the application and forming its structural elements. These scriptware may perform, among others, the following functions:
+
+- references to and links between objects;
+- global control of events;
+- requests for traces;
+- check-points management for navigation and warm-state recovery;
+- invocation of external processes and data;
+- references to other scriptware;
+- response analysis.
+
+**AVI terminal:** The particular configuration of an AVI terminal will depend on the role which will use it. As an example, an author will make use of a scanner on his AVI terminal whereas a retriever will need to consult one or several contents by simply reproducing them on his AVI terminal.
+
+**update:** Part of an application which results from the comparison between a given version of an application with a previous one.
+
+#### 3.5.2 Terms and definitions shared with ISO IEC JTC 1/SC 29/WG 12-MHEG
+
+**multimedia (representation):** The property of handling several types of representation media.
+
+The term multimedia is an adjective, it must be used attached to a noun which helps defining the context; multimedia service or application, multimedia terminal, multimedia network, multimedia presentation.
+
+In the MHEG standard, multimedia is used in the sense of multiple representation media. "Multimedia" starts with two types of representation media in a piece of information and thus a remote processing service or videotex when using only a usual keyboard and a purely textual display cannot be said multimedia as involving only one type of medium (character or text type), although in both directions, to and from the user (the service is interactive, not multimedia).
+
+**hypermedia:** The ability to access monomedia and multimedia information by interaction with explicit links.
+
+*Example* – a set of linked photographic pictures with associated sound sequences showing the famous buildings in a given town together with different views of each building; the pictures and sounds will be accessed through navigation along the predefined links within the object.
+
+**object:** Coded representation of a finite independent self-defined piece of information that can be manipulated as a whole by applications and interchanged as one unit. The information can be of multiple different types: content, projector, basic, generic input, spatio-temporal composite, clock, conditional action set and null.
+
+NOTE – This definition is not restricted to digitally coded objects, there could also be analogue objects such as videodisc sequence.
+
+**script:** Specification of how one or more objects are to be presented to, or input from a user.
+
+**scriptware (script software):** Software that realizes a script, including both informative data and associated data about how the information is to be handled/presented.
+
+## 4 Procedures
+
+It is essential that the access to the service, from the user's point of view, should be offered via a common look-and-feel for any user on any kind of implementation of it.
+
+A guidance, taking the shape of a dialogue between the user and the system operating the application, will offer the user indications and controls information.
+
+## 5 Charging principles
+
+### 5.1 General
+
+Depending on the kind of applications offered by the service or the kind of users, namely author, information manager or retriever and general public or professional accessing it, various charging principles should have to be set up.
+
+As an example, a general public user accessing an application offered by the service via a public and unattended equipment should access this service free of charge, whereas an author should subscribe to a private subscribers group and additionally, pay for the retrieval of the available information.
+
+An essential requirement is that charging must correspond to the service offered taking into account the nature of both users and applications accessed by them.
+
+### **5.2 Networks capabilities for charging**
+
+This Recommendation does not cover detailed charging principles which are to be defined in other contexts.
+
+The network should be able to charge for the use of the service on the following basis:
+
+- no charging; or
+- pay per call; and/or
+- pay per duration; and/or
+- pay per volume of transmitted information; and/or
+- pay per item.
+
+A combination of these capabilities should be set up.
+
+## **6 Quality of service**
+
+### **6.1 Network optimization**
+
+According to the different application requirements, the service will make use of the most appropriate network configuration.
+
+### **6.2 Media quality**
+
+Different applications will have a wide range of media requirements. As the AVI Service definition is independent of any application, the AVI Service will cover a generic part of them.
+
+### **6.3 Security**
+
+An AVI Service should provide the information owners with a secured environment preventing users from illegal uses of exchanged information.
+
+Security aspects are of three categories:
+
+- protection from external violations during information exchanges;
+- protection of AVI applications against use of illegal copies;
+- protection of systems themselves against unauthorized use.
+
+## **7 Interworking and intercommunication requirements**
+
+As an AVI Service does not depend on a specific network, interworking requirements have not been taken into account.
+
+Intercommunication with user-to-machine (information-type) services:
+
+The AVI Service may have to intercommunicate with the videotex service in so far as this last one defines terminals operation and access to remote databases for information retrieval purposes.
+
+Intercommunication with user-to-user (conversational-type) services:
+
+Conversational services, namely videotelephony, videoconference and audiographic conference make use of real or non real-time data transfer onto users' terminals.
+
+This facility will be used to allow intercommunication between the AVI Service and so-called conversational ones.
+
+# **Annex A** (to Recommendation F.740)
+
+## **Examples of multimedia application** (This annex forms an integral part of this Recommendation)
+
+### **A.1 Introduction**
+
+The two following examples show that the AVI Service uses three important entities which have the same role although their respective names are different:
+
+- author, creator and education author;
+- information wholesaler and educational publisher;
+- information retailer and school system.
+
+The two examples explained in this annex do not intend to be exhaustive, but aim only at showing the need for modeling an AVI Service.
+
+### **A.2 Multimedia information booth application**
+
+![Diagram of the multimedia information booth application showing the flow from Creator to Information Wholesaler, then to Information Retailer, and finally to Information Consumer across four regions.](8e14350b4b669119a3bdfca7869110ca_img.jpg)
+
+The diagram illustrates the flow of information in a multimedia information booth application. At the top, the **INFORMATION WHOLESALER (Information Manager)** is represented by a box containing a cylinder icon. Below it, the **CREATOR (Author)** is shown with four categories: **SKIING** (Sound, video, ...), **SALES** (Still images, text), **ADVERTISING** (Graphics, text), and **NEWS** (Still images). An arrow points from the Creator to the Information Wholesaler. To the right, the **INFORMATION RETAILER (Preparer)** is shown with four regions: **Region 1**, **Region 2**, **Region 3**, and **Region 4**. An arrow points from the Information Wholesaler to the Information Retailer. Below the regions, the **INFORMATION CONSUMER (Retriever)** is shown with four boxes, each receiving an arrow from one of the regions. Below these boxes, the categories **NEWS**, **ADVERTISING**, **SALES**, and **SKIING** are listed. A dashed arrow points from the Creator to the Information Consumer. The text **T0102520-92/d02** is located at the bottom right of the diagram.
+
+Diagram of the multimedia information booth application showing the flow from Creator to Information Wholesaler, then to Information Retailer, and finally to Information Consumer across four regions.
+
+NOTE – Author, information manager, preparer and retriever refer to roles which comply to the description of the AVI Service made in clause 3.
+
+**FIGURE A.1/F.740**  
+**Multimedia information booth application**
+
+#### **A.2.1 General description of the usage**
+
+A multimedia information booth service will aim at providing multimedia booths spread throughout and installed in public areas with various kinds of update information such as news, hotel reservations, entertainment, etc. To achieve this, a full range of systems will be used going from the design to collection, distribution and retrieval of information.
+
+Three entities are included in the multimedia information booth service:
+
+- **Creator (or author)** – Building multimedia applications such as news, advertising, sales, skiing;
+- **Information wholesaler** – Storing the information and managing them;
+- **Information retailer** – Distributing at a regional level the information to consumers.
+
+#### **A.2.2 Characteristics of the multimedia information application**
+
+##### **A.2.2.1 Characteristics of a service access**
+
+It provides with multi applications for many publicly available multimedia workstations like text, graphics, audio sequences, video sequences, touch screen, etc. The service access is opened 24 hours per day. Its geographic distribution allows to reach consumers in several public places. A consumer may buy things like tickets and therefore, a booth may offer a possibility of paid service. Data access may be done either local or remote. Due to the type of information, the information life cycle is short or very short and there is a high frequency of updating. Retrieval sessions are short. Terminals are installed in public places for public use and consequently they must be robust. A consumer must use the service by himself, and unattended, therefore multilingual aspect improves the service. No skill is required to use this service.
+
+##### **A.2.2.2 Information wholesaler characteristics**
+
+He is a professional and commissions new works. He must be a manager and a wholesale dealer in information. He is in charge of maintaining information. He has a “legal responsibility”. A skill in database is required.
+
+##### **A.2.2.3 Author characteristics**
+
+He is a professional author with a skill level in design and may work on one or more topics. He works in an “office” environment.
+
+##### **A.2.2.4 Information retailer characteristics**
+
+He distributes information and therefore a skill in telecommunication is required for him.
+
+### **A.3 Educational application**
+
+#### **A.3.1 General description of the usage**
+
+An educational service is used by schools to acquire and, later on, to distribute educational courses to students and tutors. As in the previous example many entities will intervene in the service.
+
+The educational service is based on three entities:
+
+- education author creates different applications like geography, mathematics, zoology;
+- education publisher sends commissions to education author to create applications, stores and manages them;
+- school system distributes the different applications to the two types of users: student and tutor.
+
+![Diagram of Educational application architecture showing roles and data flow.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+The diagram illustrates the flow of educational information. On the left, an **EDUCATIONAL AUTHOR (Author)** is shown with a box containing a cylinder icon. Below this box are three categories of content: **GEOGRAPHY** (Images, sound, graphics), **MATHEMATICS** (Text, graphics), and **ZOOLOGY** (Video, sound). An arrow points from the Author box to the **EDUCATIONAL PUBLISHER (Information Manager)** box at the top center. From the Publisher box, an arrow points to a stack of four boxes representing **SCHOOL SYSTEM (Preparer)**, labeled **School system 1**, **School system 2**, **School system 3**, and **School system 4**. A dashed arrow points from the Author's content categories to the School system 1 box. Below School system 1 are two boxes: **TUTOR (Retriever)** and **STUDENT (Retriever)**. Double-headed arrows connect both the Tutor and Student boxes to the School system 1 box. Below these boxes is a list of subjects: **ZOOLOGY**, **MATHEMATICS**, and **GEOGRAPHY**. A small code **T0102530-92/d03** is located near the Student box.
+
+Diagram of Educational application architecture showing roles and data flow.
+
+NOTE – Author, information manager, preparer and retriever refer to roles which comply to the description of the AVI Service made in clause 3.
+
+FIGURE A.2/F.740  
+**Educational application**
+
+#### A.3.2 Characteristics
+
+The two kind of users have some characteristics in common. Particularly, educational materials will be protected against illegal copy and utilization. Both users will see the same types of information: text, graphics, video sequences, audio sequences, etc.
+
+Some characteristics may be different. The tutor uses this system only at his office (during office hours) and students may use it during much more extended hours. The skill to use equipments will be medium for the tutor and basic for the student. The tutor will have a medium skill in using equipment because of his medium level workstation due to the different functionalities. Some tracks will be necessary to follow the student progress, and for the tutor course report (grades). Generally, sessions of use will be long. In case of interruption, it will be important to have a warm state recovery to start a new session at the same state when the user stopped. Other characteristics are involved for only the tutor. Information has a real-time aspect in case of on-line help. Because of the perennity of the educational material the information life cycle will be medium or long. A student may have to pay for this service. A student's terminal is composed of a low cost equipment because of its basic functionalities (only one single connection, may be remote execution...). This aspect is not critical for a tutor.

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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.740.1**
+
+(11/2019)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for an information service of  
+objects in museums**
+
+Recommendation ITU-T F.740.1
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in blue, with "ITU" in a larger, bold font above it.
+
+ITU logo
+
+International  
+Telecommunication  
+Union
+
+# ITU-T F-SERIES RECOMMENDATIONS NON-TELEPHONE TELECOMMUNICATION SERVICES
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| MOBILE SERVICE                                                  |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| TELEMATIC SERVICES                                              |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400–F.499        |
+| DIRECTORY SERVICES                                              | F.500–F.549        |
+| DOCUMENT COMMUNICATION                                          |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| ISDN SERVICES                                                   | F.800–F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850–F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.740.1
+
+## Requirements for an information service of objects in museums
+
+## Summary
+
+Recommendation ITU-T F.740.1 describes the requirements for an information service of objects in museums (ISOM). It also describes the scenarios for ISOM and the capabilities of key components of this information service, i.e., information collection unit, information storage unit, customized information presentation unit and information analysis unit. This information service can improve museum users' experience by collecting information about the exhibits and other related information from different parties and showing all the information in appropriate ways.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.740.1  | 2019-11-29 | 16          | <a href="http://handle.itu.int/11.1002/1000/14101">11.1002/1000/14101</a> |
+
+## Keywords
+
+Information consumer, information provider, objects in museum.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2020
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                             | Page |
+|-----------------------------------------------------------------------------|------|
+| 1 Scope.....                                                                | 1    |
+| 2 References.....                                                           | 1    |
+| 3 Definitions .....                                                         | 1    |
+| 3.1 Terms defined elsewhere .....                                           | 1    |
+| 3.2 Terms defined in this Recommendation.....                               | 1    |
+| 4 Abbreviations and acronyms .....                                          | 1    |
+| 5 Conventions .....                                                         | 1    |
+| 6 Overview.....                                                             | 1    |
+| 7 Scenarios for ISOM .....                                                  | 3    |
+| 7.1 Scenario 1: Visitors using multimedia devices .....                     | 3    |
+| 7.2 Scenario 2: Hearing impaired visitors with graphics/video devices ..... | 3    |
+| 7.3 Scenario 3: Visually impaired visitors with assistive devices.....      | 3    |
+| 8 Requirements for ISOM .....                                               | 3    |
+| 8.1 General requirements.....                                               | 3    |
+| 8.2 Requirements for information collection.....                            | 3    |
+| 8.3 Requirements for information storage.....                               | 4    |
+| 8.4 Requirements for customized information presentation.....               | 4    |
+| 8.5 Requirements for information analysis .....                             | 4    |
+| 9 Key components of ISOM .....                                              | 4    |
+| 9.1 Information collection unit .....                                       | 5    |
+| 9.2 Information storage unit .....                                          | 5    |
+| 9.3 Customized information presentation unit .....                          | 5    |
+| 9.4 Information analysis unit.....                                          | 5    |
+| 10 Security considerations .....                                            | 6    |
+| Bibliography.....                                                           | 7    |
+
+
+
+# **Recommendation ITU-T F.740.1**
+
+## **Requirements for an information service of objects in museums**
+
+# **1 Scope**
+
+This Recommendation describes requirements for an information service of objects in museums (ISOM). This Recommendation covers the following:
+
+- scenarios for ISOM
+- requirements of ISOM
+- key components and their functionalities.
+
+## **2 References**
+
+None.
+
+## **3 Definitions**
+
+### **3.1 Terms defined elsewhere**
+
+None.
+
+### **3.2 Terms defined in this Recommendation**
+
+None.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+ISOM Information Service of Objects in Museums
+
+## **5 Conventions**
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+- The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## **6 Overview**
+
+Traditionally, visiting a museum involves simply acquiring official information about the exhibited objects which is provided by the exhibitor using displayed text, graphics, animation, photos, sound and video. In fact, as shown in Figure 6-1, there might also exist other information generated and/or provided by other information providers. For example, researchers may discover some new findings related to the exhibited object. If the exhibited object is donated, the donator may have
+
+some stories about the object, such as, how he/she got it and why he/she decided to donate it. Even the visitors may have their own feelings and stories about the object, e.g., they may have seen another similar object in another place, to share with others [b-Nancy] [b-Angelina]. By gathering and presenting all these materials as a whole [b-Reinhard] [b-Chiayen] [b-Cesare], it is possible to form a museum community which breaks down the barriers between the museum's curators, researchers and visitors.
+
+![Diagram illustrating various sources of information about an exhibited object. A central image of a decorative square tile is surrounded by five contributors: Researcher (New findings), Museum (Official information), Donator (My stories), Visitor (My feelings), and Objects in museums. Arrows point from each contributor to the central object.](2ee59e629035d641140e55f4d215b0d7_img.jpg)
+
+The diagram shows a central image of a decorative square tile. Surrounding it are five contributors, each with an arrow pointing to the central object:
+
+- Researcher**: Associated with "New findings". The image shows a person working at a site.
+- Museum**: Associated with "Official information". The image shows a modern museum building.
+- Donator**: Associated with "My stories". The image shows hands holding a small red box.
+- Visitor**: Associated with "My feelings". The image shows a person taking a photo of an object.
+- Objects in museums**: A label with arrows pointing to the central object from the bottom.
+
+F.740.1(19)\_F6-1
+
+Diagram illustrating various sources of information about an exhibited object. A central image of a decorative square tile is surrounded by five contributors: Researcher (New findings), Museum (Official information), Donator (My stories), Visitor (My feelings), and Objects in museums. Arrows point from each contributor to the central object.
+
+**Figure 6-1 – Various sources of information about an exhibited object**
+
+In addition to the information about exhibits, there is also a lot of guidance information that can help information consumers, such as, visitors and researchers. For example, visitors should book the tickets and check transportation information before they go to the museum. When they arrive at the museum, they may have a better experience by following the recommended visiting route. It is also very useful to get information about the alarms, escape routes and emergency exits in case of emergencies such as fires or earthquakes. On the other hand, visitors may also like to provide feedback impressions about the exhibitions and the museum tour.
+
+For the visitors, it is useful to access all the information related to the exhibited objects and their visit to the museum. Visitors can use both their own multimedia devices and the public multimedia devices provided by the museum to access all this information. Considering there are many physically disabled visitors, the provided information should be adapted for ease of use. For example, the audio materials provided by the museum should be converted to text for hearing-impaired visitors. The video, text and graphics should also be converted to a form which is convenient for visually impaired visitors. Assistance information, such as barrier-free itineraries, should also be provided to impaired visitors.
+
+Above all, to improve their experiences, visitors need an information service of objects in museums (ISOM) which collects information about the exhibits and other related information from different parties and displays all this information in appropriate ways. The ISOM allows all related parties to contribute their knowledge, including adding, modifying and deleting related information. The ISOM provides an easier way to find information and exchange ideas among various parties. It can also be helpful before and after visiting the museum. This Recommendation presents the requirements of an information service of objects in museums as well as the key components and their functionalities.
+
+## **7 Scenarios for ISOM**
+
+### **7.1 Scenario 1: Visitors using multimedia devices**
+
+Visitors can use both their own multimedia devices and public multimedia devices provided by the museum to access the ISOM. The ISOM can be personalized to present a visitor with an experience customized to his/her specific interests, such as showing the information users are interested in based on users' locations. Before the visitors go to the museum, they can book the tickets, check travel routes and learn information about the exhibition provided by various entities through ISOM. When they arrive at the museum, in addition to information about the exhibited objects, visitors can also get information about the museum facilities, the itineraries which are recommended based on the visitors' interests, alarm information and escape routes and emergency exits in case of an emergency. They can also upload materials about the exhibition to ISOM (such as pictures, stories, impressions and reflections) and give feedback to the museum as well as to other visitors.
+
+### **7.2 Scenario 2: Hearing impaired visitors with graphics/video devices**
+
+The ISOM collects information from different parties. When hearing impaired visitors access the ISOM using their own devices or the public devices provided by the museum, the ISOM convert the audio part of the information to text and present it to them.
+
+### **7.3 Scenario 3: Visually impaired visitors with assistive devices**
+
+The ISOM collects information from different parties. When visually impaired visitors use their own devices or the public devices provided by the museum to access the ISOM, the ISOM converts the video, text and graphic materials to forms which can be displayed by the assistive devices such as refreshable braille displays and screen readers. The ISOM also provides visitors with information about barrier-free facilities and guides them on routes based on their location information.
+
+# **8 Requirements for ISOM**
+
+This clause presents the requirements for ISOM.
+
+### **8.1 General requirements**
+
+GEN-01: An ISOM is required to collect information about the exhibited objects.
+
+GEN-02: An ISOM is recommended to collect other related information, such as traffic, touring and weather information.
+
+GEN-03: An ISOM is required to store information collected from different parties.
+
+GEN-04: An ISOM is required to support customized information presentation.
+
+GEN-05: An ISOM is required to support information analysis.
+
+### **8.2 Requirements for information collection**
+
+IC-01: An ISOM is required to collect information about the objects-in-display in various formats, such as text, picture, audio and video.
+
+IC-02: An ISOM is required to provide methods to collect official information about exhibits from the museum.
+
+IC-03: An ISOM is required to support collecting information about visiting in the museum including barrier-free facilities, safety protection system, location system and monitoring system of the museum.
+
+IC-04: An ISOM is recommended to provide a method to collect information about other assistance information from third parties, such as the transportation suggestions for getting to the museum.
+
+IC-05: An ISOM is recommended to provide methods for visitors to contribute their own feedbacks about the exhibits, such as the photos taken by them, their stories about exhibits.
+
+IC-06: An ISOM is recommended to support collecting information about exhibited objects from third parties, such as archaeologists, artists and other researchers.
+
+### **8.3 Requirements for information storage**
+
+IS-01: An ISOM is required to store information about exhibited objects offered by different parties, such as the museum, visitors and researchers.
+
+IS-02: An ISOM is required to store other related information, such as facilities information provided by the museum and transportation information provided by the public transportation companies.
+
+IS-03: An ISOM is required to provide methods to manage information storage, such as creating, deleting and updating.
+
+### **8.4 Requirements for customized information presentation**
+
+IP-01: An ISOM is required to provide an interface for unified information accessing by visitors.
+
+IP-02: An ISOM is required to present information about exhibited objects and other related information requested by visitors.
+
+IP-03: An ISOM is required to provide information in the formats specified by visitors.
+
+IP-04: An ISOM is recommended to provide synthesized assistance information to visitors, such as visiting suggestions based on visitors' interests and their locations, and escape routes based on visitors' locations in case of an emergency.
+
+IP-05: An ISOM is required to provide an interface for visitors to access the services provided by the museum, such as booking tickets.
+
+IP-06: An ISOM is recommended to provide an interface to visitors to access the services provided by third parties, such as search engines.
+
+## **8.5 Requirements for information analysis**
+
+IA-01: An ISOM is required to analyse the feedbacks from visitors and provide the reports to the museum.
+
+IA-02: An ISOM can optionally provide the reports to third parties.
+
+# **9 Key components of ISOM**
+
+This clause describes the key components of ISOM. Figure 9-1 shows an example of the functional framework of an ISOM. An ISOM consists of five functional components: an information collection unit, an information storage unit, a customized information presentation unit and an information analysis unit. The ISOM collects information about exhibited objects and other related information from different parties, such as the museum, visitors and third parties, which is stored for further processing. The ISOM presents the information requested by the visitor and presents it in the format specified by the visitor. It can also provide analysis reports to the museum and third parties if applicable.
+
+![Figure 9-1 – Example functional framework of ISOM. The diagram shows a hierarchical functional structure. At the top, 'Third parties' (Info. on exhibit/exhibition, Service, Feedback) and 'Museum' (Safety protection system, Location system, Monitoring system, Facilities in the museum, Official info. on exhibit/exhibition, Booking system, Feedback) are connected via double-headed arrows to a central dashed box. Inside the dashed box, the 'Information collection unit' receives input from the Museum and sends it to the 'Information storage unit'. The 'Information storage unit' then feeds into the 'Customized information presentation unit' and the 'Information analysis unit'. The 'Information analysis unit' sends feedback to the 'Third parties'. At the bottom, the 'Information storage unit' is connected to a row of 'Terminal device' boxes: Multi-media device, Audio device, Graphics device, Video device, and Assistant device for disabled. The label 'F.740.1(19)_F9-1' is in the bottom right corner.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+Figure 9-1 – Example functional framework of ISOM. The diagram shows a hierarchical functional structure. At the top, 'Third parties' (Info. on exhibit/exhibition, Service, Feedback) and 'Museum' (Safety protection system, Location system, Monitoring system, Facilities in the museum, Official info. on exhibit/exhibition, Booking system, Feedback) are connected via double-headed arrows to a central dashed box. Inside the dashed box, the 'Information collection unit' receives input from the Museum and sends it to the 'Information storage unit'. The 'Information storage unit' then feeds into the 'Customized information presentation unit' and the 'Information analysis unit'. The 'Information analysis unit' sends feedback to the 'Third parties'. At the bottom, the 'Information storage unit' is connected to a row of 'Terminal device' boxes: Multi-media device, Audio device, Graphics device, Video device, and Assistant device for disabled. The label 'F.740.1(19)\_F9-1' is in the bottom right corner.
+
+**Figure 9-1 – Example functional framework of ISOM**
+
+### 9.1 Information collection unit
+
+The information collection unit is responsible for collecting information from museums, museum visitors as well as third parties. It collects official information about the exhibited objects from the museum, supplementary information about the objects from third parties such archaeologists, and user generated contents, including photos taken by visitors, their stories and feedbacks. It can also collect information about the facilities such barrier-free facilities of the museum and other assistance information from third parties, such as transportation suggestions to get to the museum.
+
+### 9.2 Information storage unit
+
+The information storage unit is responsible for storing the information gathered by the information collection unit, including information about exhibited objects offered by different parties, such as the museum, museum visitors and researchers, as well as other related information, such as facilities information provided by the museum and transportation information provided by the public transportation companies. It also provides methods to manage information storage, such as creating, deleting and updating.
+
+### 9.3 Customized information presentation unit
+
+The information presentation unit is responsible for providing an interface for unified information accessing by visitors. It presents the information requested by the visitor and presents it in the format specified by the visitor. It should convert the formats of data stored to the format appropriate for the visitors. For example, audio information should be converted to text for hearing impaired visitors. It can also provide synthesized assistance information to visitors, such as visit suggestions based on visitors' interests and their locations and escape route information based on visitors' locations in case of an emergency. It also provides interfaces to visitors to access the services provided by the museum such as booking tickets, and other services provided by third parties, such as search engine services.
+
+### 9.4 Information analysis unit
+
+The information analysis unit is responsible for analysing the feedbacks from visitors and other contents generated by visitors. Analysis reports will be generated according to the requirements of
+
+the museum. Such analysis reports can also be provided to the third parties wholly or partially as appropriate.
+
+## **10 Security considerations**
+
+It is recommended that ITU-T X-series, ITU-T Y-series and ITU-T M-series security Recommendations be taken into consideration. These include access control, authentication, data confidentiality, communications security, data integrity, availability and privacy.
+
+## Bibliography
+
+- [b-Angelina] Angelina R., Jerry W., Lynda K., Sebastian C. (2006), *How will social media affect museum communication?* In Proceedings of Nordic Digital Excellence in Museums (NODEM), Oslo, Norway.
+- [b-Cesare] Cesare R., Oliviero S., Massimo Z., Michael K., Antonio K. (2004), *The museum visit: generating seamless personalized presentations on multiple devices.* In Proceedings of the 9th international conference on Intelligent user interfaces. ACM.
+- [b-Chiayen] Chiayen C., Baorong C., Posen H. (2014), *Multimedia augmented reality information system for museum guidance.* Personal and ubiquitous computing 18.2: 315-322.
+- [b-Nancy] Nancy P. (2010), *Digital: Museum as platform, curator as champion, in the age of social media.* Curator: The Museum Journal 53.1: 35-43.
+- [b-Reinhard] Reinhard O., Marcus S. (1999), *A nomadic information system for adaptive exhibition guidance.* Archives and museum informatics 13.2: 127-138.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,528 @@
+
+
+# Recommendation **ITU-T F.740.12 (12/2025)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+## **Metadata for a cultural relics and artworks tracing system based on distributed ledger technology**
+
+![ITU logo](6ed175c791b5e156d9c98a8dbcc3318c_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font overlaid on the globe.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.740.12
+
+# Metadata for a cultural relics and artworks tracing system based on distributed ledger technology
+
+## Summary
+
+Recommendation ITU-T F.740.12 outlines the metadata framework for a cultural relics and artworks tracing system (CRATS) based on distributed ledger technology (DLT). CRATS aims to enhance the traceability, security and transparency of cultural relics and artworks (CRA) throughout their lifecycle. The framework consists of three core components: the universally recognized digital identity (URDI) component, the multidimensional description (MD) component, and the full lifecycle record (FLR) component. These components collectively support the recording of events throughout a CRA object's lifecycle, such as provenance tracking, inventory management, insurance management, market monitoring, etc., ensuring all associated data for CRA is archived in an immutable, timestamped evidence chain.
+
+This Recommendation is applicable to cultural institutions, digital platforms, and related entities engaged in the registration, management, or monitoring of cultural relics and artworks (CRA) using a distributed ledger technology (DLT) based tracing system.
+
+Implementation-specific details such as blockchain platform configuration, cryptographic algorithms, consensus mechanisms, or user-interface designs are outside the scope of this Recommendation.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.740.12 | 2025-12-14 | 21          | 11.1002/1000/16573 |
+
+## Keywords
+
+Artworks, cultural relics, cultural relics and artworks tracing system, distributed ledger technology, metadata.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2026
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                   | Page |
+|---------------------------------------------------|------|
+| 1 Scope.....                                      | 1    |
+| 2 References.....                                 | 1    |
+| 3 Definitions .....                               | 1    |
+| 3.1 Terms defined elsewhere .....                 | 1    |
+| 3.2 Terms defined in this Recommendation.....     | 2    |
+| 4 Abbreviations and acronyms .....                | 2    |
+| 5 Conventions .....                               | 2    |
+| 6 CRATS workflow .....                            | 2    |
+| 7 Metadata for CRATS.....                         | 5    |
+| 7.1 An overview of the metadata for CRATS .....   | 5    |
+| 7.2 Universally recognized digital identity ..... | 5    |
+| 7.3 Multidimensional description component .....  | 7    |
+| 7.4 Full lifecycle record.....                    | 9    |
+| Annex A – The main material of CRA .....          | 11   |
+| Annex B – Full lifecycle record type .....        | 16   |
+| Bibliography.....                                 | 19   |
+
+
+
+# Recommendation ITU-T F.740.12
+
+## Metadata for a cultural relics and artworks tracing system based on distributed ledger technology
+
+## 1 Scope
+
+This Recommendation is to define the metadata framework for cultural relics and artworks tracing system (CRATS). It specifies universally recognized digital identity (URDI), multidimensional description (MD), and the full lifecycle record (FLR) required to create a unique, immutable, and verifiable digital identity and a traceable lifecycle record for each cultural relics and artworks (CRA).
+
+The scope of this Recommendation includes:
+
+- 1) Cultural relics and artworks tracing system workflow.
+- 2) Metadata for a cultural relics and artworks tracing system.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ISO 639] ISO 639:2023, *Code for individual languages and language groups*.
+- [ISO 8601-1] ISO 8601-1:2019, *Date and time – Representations for information interchange – Part 1: Basic rules*.
+- [ISO 80000-1] ISO 80000-1:2022, *Quantities and units – Part 1: General*.
+- [ISO 80000-3] ISO 80000-3:2019, *Quantities and units – Part 3: Space and time*.
+- [ISO 80000-4] ISO 80000-4:2019, *Quantities and units – Part 4: Mechanics*.
+
+# 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+- 3.1.1 blockchain** [b-ITU-T F.751.0]: A type of distributed ledger that is composed of digitally recorded data arranged as a successively growing chain of blocks with each block cryptographically linked and hardened against tampering and revision.
+- 3.1.2 distributed ledger technology (DLT)** [b-ITU-T F.751.0]: Technology enabling large groups of nodes in distributed ledger networks to reach agreement and record information without the need for a central authority.
+- 3.1.3 metadata** [b-ITU-T X.1255]: Structured information that pertains to the identity of users, systems, services, processes, resources, information or other entities.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 cultural relics and artworks:** Tangible and movable objects of historical, artistic, archaeological or cultural value that represent human creativity or heritage.
+
+**3.2.2 full lifecycle record:** A tamper-evident metadata component that logs, timestamps and anchors all critical transactional events associated with an object of cultural relics and artworks throughout its existence.
+
+**3.2.3 market monitoring:** The continuous observation, analysis and recording of market activities related to cultural relics and artworks, such as auctions and private sales, to ensure transparency, and prevent fraud or manipulation.
+
+**3.2.4 multidimensional description:** Multidimensional description is culturally contextual information that enriches the universal digital identity of cultural relics and artworks by providing diverse interpretations and associations from various cultural perspectives.
+
+**3.2.5 provenance tracking:** The systematic documentation and verification of the chronological history of ownership, custody, location, condition, etc. of an object of cultural relics and artworks from its origin to the present.
+
+**3.2.6 universally recognized digital identity:** A standardized digital identifier for cultural relics and artworks, derived from immutable, objectively verifiable attributes (e.g., material composition, creation era, etc.).
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                             |
+|-------|---------------------------------------------|
+| CRA   | Cultural Relics and Artworks                |
+| CRATS | Cultural Relics and Artworks Tracing System |
+| DLT   | Distributed Ledger Technology               |
+| FLR   | Full Lifecycle Record                       |
+| MD    | Multidimensional Description                |
+| URDI  | Universally Recognized Digital Identity     |
+
+# 5 Conventions
+
+None.
+
+# 6 CRATS workflow
+
+The lack of a unified system and metadata standards for CRA data recording and tracking gives rise to difficulties in the cross-platform circulation and sharing of CRA information. Cultural relics and artworks tracing system (CRATS) is designed to meet the requirements for consistent digital management and traceability of CRA across institutions and systems, thereby supporting collaboration among museums, digital platforms and other cultural entities.
+
+CRATS uses a DLT-based system to provide secure, transparent and standardized management of a CRA object. Data for CRA is organized through a metadata framework, with participating institutions such as museums registering new artifacts by creating digital identities and uploading detailed descriptions. This Recommendation specifies the metadata applicable to CRA information circulating within the CRATS system. The CRATS system shall be implemented using distributed ledger technology (DLT) in order to take advantage of its technical characteristics, namely decentralization,
+
+immutability and transparency. These characteristics are intended to support the sharing and interoperability of data for CRA across different entities and platforms. Throughout each CRA object's lifecycle, any state changes, such as transfers or restorations, are recorded via registered user terminals, while observers can query but not alter records, ensuring oversight and data for CRA integrity. The system also manages personal and organizational profiles and every action, such as registration and update is immutably logged on the blockchain, making the entire history and status of each CRA object traceable, verifiable and protected against tampering.
+
+The system's workflow is shown in Figure 1.
+
+The workflow of the CRATS system comprises three primary roles: participants, CRATS and observers. Participants shall register through a user terminal by providing personal or organizational information. Upon registration, participants register CRA data for the purpose of generating digital identities and multidimensional descriptions of CRA. The recording of data changes for CRA within the system shall be managed through a metadata framework to maintain complete lifecycle records of CRA information. The CRATS entity is responsible for processing such information. Both participants and observers may submit queries of data for CRA to the CRATS system. The CRATS system shall process these queries and facilitate the transmission of CRA information accordingly. The overall process is implemented on the basis of distributed ledger technology (DLT), in order to ensure decentralization, immutability and transparency in data handling for CRA.
+
+![Figure 1 – CRATS workflow diagram showing interactions between Participant, CRATS, and Observer roles, supported by Distributed ledger technology.](b3baf3a29b67c7425d2562ddbc52f0cc_img.jpg)
+
+The diagram illustrates the CRATS workflow involving three main roles: Participant, CRATS, and Observer, supported by Distributed ledger technology (DLT).
+
+- Participant:**
+  - Registration:** Uses a "Registered user terminal" to send "User registration" to CRATS.
+  - State change:** Provides "CRA unstructured data" to CRATS for "CRA data registration" and "CRA data change recording".
+  - Query:** Sends a "User query" to CRATS, which responds with "CRA data query".
+- CRATS:**
+  - Manages "Personal/Organizational information" via "User login" from the Observer.
+  - Processes CRA data into three components: "Universally recognized digital identity", "Multidimensional description", and "Full lifecycle record".
+  - Handles "CRA data query" from the Observer and "User query" from the Participant.
+  - Facilitates "CRA information transmission" to the DLT layer.
+- Observer:**
+  - Performs "User login" to access CRATS.
+  - Sends "CRA data query" to CRATS and receives "User query" in response.
+- Distributed ledger technology (DLT):**
+  - Consists of three smart contracts: "Consensus-based digital identity management smart contract", "Multidimensional description component management smart contract", and "Full lifecycle record management smart contract".
+  - Receives "CRA information transmission" from CRATS.
+
+Figure 1 – CRATS workflow diagram showing interactions between Participant, CRATS, and Observer roles, supported by Distributed ledger technology.
+
+F.740.12(25)
+
+**Figure 1 – CRATS workflow**
+
+Figure 2 illustrates the workflow for registering data for CRA. In this workflow, a participant begins by registering their user information within the CRATS. Next, the participant submits a digital identity record for a CRA object, ensuring each object is uniquely identified on the blockchain. They then provide an MD record, detailing various attributes such as provenance, physical characteristics, historical context, etc. The current state information of the object, such as location, condition, or ownership, is also recorded. Finally, all submitted data for CRA and changes are committed to the blockchain as evidence records, creating an immutable and verifiable history for each CRA object.
+
+This process ensures that every step of registration is securely documented, traceable and protected against tampering.
+
+![Figure 2 – CRA data registration workflow diagram](f4fdd410cdb84df81274da55721e56fb_img.jpg)
+
+The diagram illustrates the CRA data registration workflow. It features two main components: a 'Participant' on the left, represented by a rounded rectangle, and 'CRATS' on the right, represented by a rectangle. Six horizontal arrows point from the Participant to CRATS, representing the following steps: 'Register user information', 'Submit CRA digital identity', 'Record multidimensional description', 'Record CRA state information', 'Commit evidence record', and a final unlabeled arrow. The label 'F.740.12(25)' is positioned at the bottom right of the diagram.
+
+Figure 2 – CRA data registration workflow diagram
+
+**Figure 2 – CRA data registration workflow**
+
+Figure 3 illustrates the workflow for recording changes in the data for CRA. In this workflow, a participant initiates updates to the records of a CRA object by submitting state changes to its digital identity, MD, or current state information. These updates may include modifications to ownership details, physical attributes, provenance, condition, location, etc. Once the changes are made, all updated information is committed to the blockchain as evidence records. This ensures that every alteration in the object's status is securely logged, creating an immutable and transparent history that supports traceability, accountability and protection against unauthorized modifications.
+
+![Figure 3 – CRA data change recording workflow diagram](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg)
+
+The diagram illustrates the CRA data change recording workflow. It features two main components: a 'Participant' on the left, represented by a rounded rectangle, and 'CRATS' on the right, represented by a rectangle. Five horizontal arrows point from the Participant to CRATS, representing the following steps: 'Change CRA digital identity', 'Change multidimensional description', 'Change CRA state information', 'Commit evidence record', and a final unlabeled arrow. The label 'F.740.12(25)' is positioned at the bottom right of the diagram.
+
+Figure 3 – CRA data change recording workflow diagram
+
+**Figure 3 – CRA data change recording workflow**
+
+Figure 4 illustrates the workflow for querying data for CRA. In this workflow, an observer interacts with the CRATS by submitting a query request to access information stored on the blockchain. Upon receiving the request, the system returns relevant data for CRA, including the digital identity, MD and current state information of a CRA object. This process allows observers, such as auditors, regulators, or researchers, to retrieve comprehensive and up-to-date records without altering any data for CRA, ensuring transparency, accountability and secure access to the verified information.
+
+![Figure 4 – CRA data query workflow diagram showing the interaction between an Observer and CRATS. The Observer sends a 'Submit query request' to CRATS. CRATS returns four pieces of information: 'Return CRA digital identity', 'Return multidimensional description', 'Return CRA state information', and 'F.740.12(25)'.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+```
+
+graph LR
+    Observer[Observer] -- "Submit query request" --> CRATS[CRATS]
+    CRATS -- "Return CRA digital identity" --> Observer
+    CRATS -- "Return multidimensional description" --> Observer
+    CRATS -- "Return CRA state information" --> Observer
+    CRATS -- "F.740.12(25)" --> Observer
+  
+```
+
+Figure 4 – CRA data query workflow diagram showing the interaction between an Observer and CRATS. The Observer sends a 'Submit query request' to CRATS. CRATS returns four pieces of information: 'Return CRA digital identity', 'Return multidimensional description', 'Return CRA state information', and 'F.740.12(25)'.
+
+Figure 4 – CRA data query workflow
+
+# 7 Metadata for CRATS
+
+## 7.1 An overview of the metadata for CRATS
+
+Metadata is fundamental to the effective tracing and management of CRA in a DLT-based system. It specifies the essential elements needed to uniquely identify, describe and monitor each object throughout its lifecycle, encompassing attributes such as provenance, physical characteristics, ownership history, condition assessments and exhibition records. By establishing authoritative and rigorous metadata standards, this chapter provides the foundation for transparent, verifiable and consistent documentation, facilitating secure information sharing and reliable traceability across institutions and platforms.
+
+## 7.2 Universally recognized digital identity
+
+A standardized digital identifier for CRA, derived from immutable, objectively verifiable attributes (e.g., material composition, creation era, etc.). This identity establishes a culture-agnostic foundation recognized across institutional and national boundaries, enabling tamper-proof authentication within CRATS.
+
+The elements of universally recognized digital identity (URDI) are given in Table 1.
+
+Table 1 – Elements of URDI
+
+| Element_name  | Data type | Description                                                                                                                                                               | Controlled vocabulary | Mandatory (M) or optional (O) |
+|---------------|-----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------|-------------------------------|
+| object_id     | Integer   | The object_id represents the ID of the CRA object, long integer, unique and increasing, with a maximum length of 20.                                                      | No                    | M                             |
+| object_name   | String    | A string denoting the name of the CRA object.                                                                                                                             | No                    | M                             |
+| language_code | String    | It represents the language for the value of the artifact metadata field. It can be selected according to the language of the data source for CRA. Refer to the [ISO 639]. | Yes                   | M                             |
+| material      | String    | A string describing the main material forming the CRA object.                                                                                                             | Yes                   | M                             |
+
+**Table 1 – Elements of URDI**
+
+| <b>Element_name</b> | <b>Data type</b> | <b>Description</b>                                                                                                                                                          | <b>Controlled vocabulary</b> | <b>Mandatory (M) or optional (O)</b> |
+|---------------------|------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|--------------------------------------|
+|                     |                  | The value shall be taken from Table A.1 or may refer to an other_material_id in Table A.2 if no suitable material exists in Table A.1.                                      |                              |                                      |
+| techniques          | String           | A string listing any production or manufacturing skills and processes used in creating the CRA object.                                                                      | No                           | O                                    |
+| current_location    | String           | A string indicating the current physical location of the CRA object.                                                                                                        | No                           | M                                    |
+| creation_location   | String           | A string specifying the location where the CRA object was created or originated.                                                                                            | No                           | M                                    |
+| creator_name        | String           | A string that refers to the name or pseudonym of the person who created the CRA object.                                                                                     | No                           | O                                    |
+| object_description  | String           | A string providing detailed information on the physical and visual characteristics of the CRA object, as well as any identifying features.                                  | No                           | O                                    |
+| subject             | String           | A string describing the main theme or message conveyed by the CRA object, whether abstract or figurative, including the narrative or iconographic content.                  | No                           | O                                    |
+| dimension           | String           | A string representing the physical dimensions of the CRA object, expressed in accordance with the definitions and conventions specified in [ISO 80000-1] and [ISO 80000-3]. | Yes                          | M                                    |
+| mass                | String           | A string indicating the mass of the CRA object, expressed in accordance with the definitions and conventions specified in                                                   | Yes                          | M                                    |
+
+**Table 1 – Elements of URDI**
+
+| <b>Element_name</b>     | <b>Data type</b> | <b>Description</b>                                                                                                                                                                      | <b>Controlled vocabulary</b> | <b>Mandatory (M) or optional (O)</b> |
+|-------------------------|------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|--------------------------------------|
+|                         |                  | [ISO 80000-1] and [ISO 80000-4].                                                                                                                                                        |                              |                                      |
+| quantity                | Integer          | An integer specifying the number of objects in the CRA set or series.                                                                                                                   | No                           | M                                    |
+| created_time            | String           | A string representing the time or historical period associated with the creation of the CRA object, formatted according to [ISO 8601-1], and using the anno domini (AD) chronology.     | Yes                          | O                                    |
+| styles/groups/movements | String           | A string providing a description that links the CRA object to a specific style, historical period, group, school, or movement, based on the characteristics depicted in the CRA object. | No                           | O                                    |
+| inscriptions or marks   | String           | A string detailing any distinguishing physical marks, letters, texts, annotations, or labels affixed or applied to the CRA object.                                                      | No                           | O                                    |
+| current_condition       | String           | A string assessing the physical state, characteristics and completeness of the CRA object at a specific point in time.                                                                  | No                           | O                                    |
+
+## 7.3 Multidimensional description component
+
+Multidimensional description (MD) refers to the information that provides a comprehensive, contextual understanding of a CRA object from various cultural perspectives. This includes information about the object's attributes across different cultures, related objects and associated knowledge. These multidimensional data elements for CRA enrich the object's information by offering diverse interpretations, thus complementing the URDI. The MD provides a more complete representation of a CRA object within its broader cultural and historical context.
+
+The elements of MD are given in Table 2.
+
+**Table 2 – Elements of MD**
+
+| <b>Element_name</b>        | <b>Data type</b> | <b>Description</b>                                                                                                                                                             | <b>Controlled vocabulary</b> | <b>Mandatory (M) or optional (O)</b> |
+|----------------------------|------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|--------------------------------------|
+| object_id                  | Int              | Object_id represents the ID of the CRA object, long integer, unique and increasing, with a maximum length of 20.                                                               | No                           | M                                    |
+| language_code              | String           | It represents the language for the value of the artifact metadata field. It can be selected according to the language of the data source for CRA. Refer to [ISO 639] standard. | Yes                          | M                                    |
+| record_entity              | String           | A string identifying the entity that initiates the recording of information related to the CRA object on the blockchain.                                                       | No                           | M                                    |
+| record_time                | Datetime         | A datetime value indicating the exact time when the additional information about the CRA object was recorded.                                                                  | No                           | M                                    |
+| record_location            | String           | A string indicating the location of the entity that recorded the additional information about the artifact.                                                                    | No                           | M                                    |
+| record_purpose_description | String           | A string that provides a detailed explanation of the purpose or rationale behind recording the additional information.                                                         | No                           | M                                    |
+| additional_name            | String           | A string indicating names used across different cultures for the same CRA object.                                                                                              | No                           | O                                    |
+| additional_category        | String           | A string representing the category or classification assigned to the CRA object in different cultural contexts or systems.                                                     | No                           | O                                    |
+| additional_periods         | String           | A string denoting the historical periods associated with the CRA object, as used in                                                                                            | No                           | O                                    |
+
+**Table 2 – Elements of MD**
+
+| <b>Element_name</b>                | <b>Data type</b> | <b>Description</b>                                                                                                                                  | <b>Controlled vocabulary</b> | <b>Mandatory (M) or optional (O)</b> |
+|------------------------------------|------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|--------------------------------------|
+|                                    |                  | different cultural or historical contexts.                                                                                                          |                              |                                      |
+| additional_styles/groups/movements | String           | A string that describes the art styles, groups, or movements to which the CRA object is linked, as recognized in various cultural contexts.         | No                           | O                                    |
+| related_objects                    | String           | A string describing other CRA objects that are related to the one being described.                                                                  | No                           | O                                    |
+| cultural_context                   | String           | A string that provides information about the culture, nation, or country, or the cultural background in which the CRA object exists or was created. | No                           | O                                    |
+| related_knowledge                  | String           | A string that encompasses information about people, events, research, terminology and other relevant data associated with the CRA object.           | No                           | O                                    |
+
+Some metadata in the MD component can be mapped with the corresponding metadata in the URDI component, for example:
+
+- a) The MD field additional\_periods corresponds to the URDI field created\_time.
+- b) The MD field additional\_name corresponds to the URDI field object\_name.
+- c) The MD fields additional\_styles, additional\_groups and additional\_movements correspond to the URDI fields styles, groups and movements, respectively.
+
+## **7.4 Full lifecycle record**
+
+A tamper-evident metadata component that logs, timestamps and anchors all critical transactional events associated with a CRA object throughout its existence. This includes provenance tracking (creation, circulation, restoration, exhibition and other activities), inventory management, compliance, insurance management, market monitoring, etc. By converting these events into DLT-validated cryptographic proofs, full lifecycle record (FLR) establishes an immutable evidence chain that extends the CRA static identity with dynamic operational historicity.
+
+The elements of FLR are given in Table 3.
+
+**Table 3 – Elements of FLR**
+
+| <b>Element_name</b>     | <b>Data type</b> | <b>Description</b>                                                                                                                                                                                                                                                                          | <b>Controlled vocabulary</b> | <b>Mandatory (M) or optional (O)</b> |
+|-------------------------|------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|--------------------------------------|
+| object_id               | Int              | Object_id represents the ID of the CRA object, long integer, unique and increasing, with a maximum length of 20.                                                                                                                                                                            | No                           | M                                    |
+| object_owner            | String           | A string representing the individual or institution that holds the rights to possess and control the CRA object. This right is called ownership.                                                                                                                                            | No                           | M                                    |
+| object_holder           | String           | A string referring to the individual or institution that physically possesses or temporarily controls the CRA object. This entity may not necessarily hold ownership rights.                                                                                                                | No                           | M                                    |
+| relevant third party    | String           | A string identifying regulatory bodies, certification agencies, or entities involved in enforcing compliance, auditing transactions, or resolving disputes related to the CRA object.                                                                                                       | No                           | O                                    |
+| FLR_type                | String           | A string describing the type of FLR. The value is required to be selected from the sub-category code specified in Table B.1, which defines the FLR type classification within the CRATS framework, or from the other_FLR_id specified in Table B.2 if no suitable type exists in Table B.1. | Yes                          | M                                    |
+| record_data_location    | String           | A string representing the location where the event took place, such as the venue or institution hosting the event.                                                                                                                                                                          | No                           | M                                    |
+| record_data_date        | Date             | A date representing the specific time when an event in the full lifecycle of the CRA object occurred.                                                                                                                                                                                       | No                           | M                                    |
+| record_data_description | String           | A string providing a detailed description of the FLR. This may include provenance tracking, inventory management, compliance, insurance management, market monitoring, or other related information.                                                                                        | No                           | O                                    |
+
+## Annex A
+
+### The main material of CRA
+
+(This annex forms an integral part of this Recommendation.)
+
+Table A.1 specifies the classification of the main materials used in cultural relics and artworks (CRA). This classification defines a controlled vocabulary intended to ensure consistent representation of material types across different CRA objects. The categories include inorganic materials, organic materials, composite materials, digital works and an "other" category for unclassified or emerging materials. Each category is further subdivided into sub-categories to provide a more specific classification. The sub-category code is required to be used as the data value of the "material" element in Table 1 elements of URDI, in accordance with the controlled vocabulary defined in this Recommendation.
+
+**Table A.1 – Main material of CRA**
+
+| Category code | Category  | Sub-category code | Sub-category | Examples of CRA                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+|---------------|-----------|-------------------|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>NOG</b>    | Inorganic | <b>NOG-01</b>     | Ceramics     | Ceramics encompasses earthenware and porcelain, formed by processing clay and other natural minerals through proportioning, crushing, shaping and high-temperature firing, resulting in a hard material. Among the CRA artifacts, there are ceramics such as: Tang Sancai pottery, Chinese porcelain, ancient Greek amphorae, Egyptian faience beads, Roman terra sigillata, Persian lusterware, Iznik ware, Meissen porcelain, etc.                       |
+| <b>NOG</b>    | Inorganic | <b>NOG-02</b>     | Glass        | Glass is an inorganic amorphous solid featuring a disordered atomic structure, formation via rapid melt cooling to avoid crystallization, and a reversible rigid-to-viscous transition at the glass transition temperature. Among the CRA artifacts, there are glasses such as: Egyptian faience, Roman glass vessels, Beijing glass, Islamic glass lamps, Venetian glass, Egyptian glass inlays, Byzantine glass mosaics, Baccarat, Lalique, Murano, etc. |
+| <b>NOG</b>    | Inorganic | <b>NOG-03</b>     | Metals       | Metals are crystalline materials with delocalized electrons that enable high electrical/thermal conductivity, malleability, ductility and characteristic luster. Among the CRA artifacts, there are metal works such as: Chinese bronze vessels, Greek bronze helmets, Roman silver coins,                                                                                                                                                                 |
+
+**Table A.1 – Main material of CRA**
+
+| <b>Category code</b> | <b>Category</b> | <b>Sub-category code</b> | <b>Sub-category</b> | <b>Examples of CRA</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+|----------------------|-----------------|--------------------------|---------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                      |                 |                          |                     | African iron tools, Celtic shields, Indian gold jewellery, etc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| <b>NOG</b>           | Inorganic       | <b>NOG-04</b>            | Minerals & pigments | Artifacts decorated with mineral-based pigments typically feature surfaces coloured through application of these ground minerals, as opposed to objects wholly sculpted from pigment material. The following typology categorizes key artifacts by function and cultural context: Lascaux cave in France, Altamira in Spain, aboriginal Australian art, Egyptian & Mesopotamian painted potteries, black-figure potteries from Greek & Roman, wall paintings and tomb paintings from China & Egypt, Chinese Tangka paintings, etc. |
+| <b>NOG</b>           | Inorganic       | <b>NOG-05</b>            | Plaster & mortar    | Plaster, a smooth paste applied as a protective or decorative coating to architectural surfaces (e.g., walls, ceilings), cures into a hard, durable layer. Mortar, in contrast, serves primarily as a binding agent for masonry. Key artifacts by function and cultural context: Plaster was integral to diverse cultural traditions, including Roman frescoes, Egyptian tomb paintings, Greek stucco reliefs, Chinese tomb murals, Islamic decorative plasterwork, Mesoamerican stucco murals, etc.                               |
+| <b>NOG</b>           | Inorganic       | <b>NOG-06</b>            | Stone               | Naturally occurring, inorganic solids with definite chemical composition and crystalline structure quartz, such as: Feldspar, Mica, Calcite, Diamond, etc. Among the CRA artifacts, there are stone works such as: Egyptian limestone statues, Greek marble sculptures, Roman stone inscriptions, Indian sandstone reliefs, Chinese jade carvings, Mayan stelae, etc.                                                                                                                                                              |
+| <b>NOG</b>           | Inorganic       | <b>NOG-07</b>            | Other inorganic     | This category covers inorganic materials not otherwise classified in the preceding sub-categories (e.g., ceramics, glass, metals, minerals & pigments, plaster & mortar, stone). It serves as a placeholder for materials of inorganic origin that do not clearly                                                                                                                                                                                                                                                                  |
+
+**Table A.1 – Main material of CRA**
+
+| <b>Category code</b> | <b>Category</b> | <b>Sub-category code</b> | <b>Sub-category</b>     | <b>Examples of CRA</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+|----------------------|-----------------|--------------------------|-------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                      |                 |                          |                         | fit existing types or represent newly identified material.                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+| <b>OG</b>            | Organic         | <b>OG-01</b>             | Plant materials         | Plant materials are materials derived directly from plants, encompassing both living and non-living matter, in natural or processed states, widely employed for the CRA objects, such as: Chinese calligraphy and Chinese painting, European illuminated manuscripts, Egyptian papyrus work, Indian palm leaf manuscripts, African woven baskets, etc.                                                                                                                                              |
+| <b>OG</b>            | Organic         | <b>OG-02</b>             | Animal-derived products | Animal-derived products are materials derived directly from non-human animals, encompassing raw or processed organic matter obtained from their bodies, utilized across scientific, artistic and historical domains. The CRA objects that have been handed down from history, such as: horn cups, parchment /vellum manuscripts, ivory carvings, etc.                                                                                                                                               |
+| <b>OG</b>            | Organic         | <b>OG-03</b>             | Other organic           | This category includes organic materials not covered by the previous sub-categories (e.g., plant or animal-derived products). It may encompass newly discovered or synthetic organic material derived from biological sources, or materials whose classification remains uncertain.                                                                                                                                                                                                                 |
+| <b>CP</b>            | Composite       | <b>CP-01</b>             | Multi-material          | In the context of cultural heritage and art conservation, multi-material refers to an artifact, artwork, or object intentionally crafted from two or more distinct materials (organic, inorganic, synthetic, or composite) that are integrated structurally, functionally, or decoratively. Among the CRA artefacts, such as Chinese lacquered wood with gold inlay, Indian ivory inlaid into wood furniture, Roman mosaic floors, Islamic metalwork with enamel, African beadwork on leather, etc. |
+| <b>CP</b>            | Composite       | <b>CP-02</b>             | Mixed media             | The term as a formal art classification emerged in the mid-20th century. It refers to artworks created by intentionally combining two or more                                                                                                                                                                                                                                                                                                                                                       |
+
+**Table A.1 – Main material of CRA**
+
+| <b>Category code</b> | <b>Category</b> | <b>Sub-category code</b> | <b>Sub-category</b> | <b>Examples of CRA</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+|----------------------|-----------------|--------------------------|---------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                      |                 |                          |                     | distinct artistic mediums on a single support (e.g., canvas, paper, board), where the juxtaposition of materials becomes an essential aspect of the work's conceptual, textural, or aesthetic expression. Unlike traditional single-medium works (e.g., oil painting), mixed media embraces hybridity and material experimentation as central to its practice. This technique was employed by artists such as: Pablo Picasso, Georges Braque, Kurt Schwitters, Max Ernst, Robert Rauschenberg and many more.                                                                                                                                                                                              |
+| <b>CP</b>            | Composite       | <b>CP-03</b>             | Other composite     | This category encompasses composite or mixed material not defined in the previous sub-categories (e.g., multi-material, mixed media). It is intended to record hybrid compositions or structurally integrated material that exhibits composite characteristics but does not conform to established categories.                                                                                                                                                                                                                                                                                                                                                                                            |
+| <b>DG</b>            | Digital         | <b>DG-01</b>             | Digital works       | Digital art refers to artistic practices where computational technologies serve as the primary medium, tool, or conceptual framework for creation, display, or distribution. It is characterized by: binary logic: artworks generated, processed, or stored as digital data (0s/1s); algorithmic agency: use of code, algorithms, AI, or interactive systems; immateriality: existence as mutable data, distinct from physical artifacts. Among the CRA works, such as: Ben Laposky's work named "oscillons", works from JODI, Amiga paintings from Andy Warhol, etc. From the 2000s to the present, digital art has evolved through the democratization of AI/VR tools and the emergence of NFT markets. |
+| <b>DG</b>            | Digital         | <b>DG-02</b>             | Other digital works | This category refers to digital or computationally based CRA works that are not represented by the preceding sub-category (digital works). It covers emerging or                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+
+**Table A.1 – Main material of CRA**
+
+| <b>Category code</b> | <b>Category</b> | <b>Sub-category code</b> | <b>Sub-category</b>                | <b>Examples of CRA</b>                                                                                                                    |
+|----------------------|-----------------|--------------------------|------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------|
+|                      |                 |                          |                                    | experimental forms of digital expression.                                                                                                 |
+| <b>OTH</b>           | Other           | <b>OTH-01</b>            | Unclassified or emerging materials | Materials that are not included in the above categories. When this category is selected, additional details may be recorded in Table A.2. |
+
+Table A.2 defines an open structure that allows the registration of additional materials not listed in Table A.1. Each record represents a material categorized under "other" in Table A.1 and is identified by a unique other\_material\_id.
+
+**Table A.2 – Other material of CRA**
+
+| <b>Element_name</b> | <b>Data type</b> | <b>Description</b>                                                                                                                                                                                        |
+|---------------------|------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| other_material_id   | String           | A unique identifier is assigned to each additional material. The identifier shall follow the format "OM-XXXX", where "XXXX" represents a sequential alphanumeric code assigned by the registering system. |
+| other_material_name | String           | Free-text name of a material not represented in Table A.1 (the controlled vocabulary).                                                                                                                    |
+
+NOTE – Table A.2 provides flexibility for CRATS users to record new materials not listed in Table A.1.
+
+## Annex B
+
+### Full lifecycle record type
+
+(This annex forms an integral part of this Recommendation.)
+
+Table B.1 defines the classification of full lifecycle record (FLR) types applicable to CRA within the CRATS framework. This classification establishes a controlled vocabulary that enables consistent representation of lifecycle event types, including identity creation, physical state changes, knowledge and authentication updates, provenance and rights management, exhibitions and publications. Each category is further subdivided into sub-categories to provide a more specific classification. The sub-category code is required to be used as the data value of the "FLR type" element in Table 3 elements of FLR, in accordance with the controlled vocabulary defined in this Recommendation.
+
+**Table B.1 – FLR type**
+
+| Category code | Category              | Sub-category code | Sub-category                         | Description                                                                                                                                   |
+|---------------|-----------------------|-------------------|--------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>IC</b>     | Identity creation     | <b>IC-01</b>      | Initial on-chain registration        | Captures the object's foundational digital record on-chain, including cryptographic hashes of key metadata, establishing its unique identity. |
+| <b>IC</b>     | Identity creation     | <b>IC-02</b>      | Digital twin association             | Documents the secure linkage between a physical object and its digital representation (token), using technical and physical evidence.         |
+| <b>IC</b>     | Identity creation     | <b>IC-03</b>      | Physical identifier assignment       | Records the assignment of a unique physical identifier (barcode, RFID, microchip, etc.) for traceability and authentication.                  |
+| <b>PC</b>     | Physical state change | <b>PC-01</b>      | Condition report update              | Logs any observed changes in the object's physical state, with timestamped documentation and report hash.                                     |
+| <b>PC</b>     | Physical state change | <b>PC-02</b>      | Restoration & conservation treatment | Details interventions for stabilization, restoration, or conservation, recording methods, materials and outcomes.                             |
+| <b>PC</b>     | Physical state change | <b>PC-03</b>      | Scientific analysis record           | Registers results of scientific analyses, providing hashes of reports and linking findings to the object's history.                           |
+
+**Table B.1 – FLR type**
+
+| <b>Category code</b> | <b>Category</b>            | <b>Sub-category code</b> | <b>Sub-category</b>                 | <b>Description</b>                                                                                                                 |
+|----------------------|----------------------------|--------------------------|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------|
+| <b>PC</b>            | Physical state change      | <b>PC-04</b>             | Component change                    | Documents the addition, removal, or replacement of any separable or integral component, including reasons and responsible parties. |
+| <b>PC</b>            | Physical state change      | <b>PC-05</b>             | Relocation/movement record          | Tracks the movement or relocation of the object, including packing, transport and chain of custody.                                |
+| <b>PC</b>            | Physical state change      | <b>PC-06</b>             | Official declaration of destruction | Confirms the object's complete destruction, including supporting evidence.                                                         |
+| <b>KA</b>            | Knowledge & authentication | <b>KA-01</b>             | Change in attribution               | Updates the recognized creator, origin, or school based on new research or expert consensus.                                       |
+| <b>KA</b>            | Knowledge & authentication | <b>KA-02</b>             | Authenticity verification           | Records authoritative conclusions on authenticity, with certificate hashes stored on-chain.                                        |
+| <b>KA</b>            | Knowledge & authentication | <b>KA-03</b>             | Correction of dating                | Revises the estimated creation date based on new research or evidence.                                                             |
+| <b>KA</b>            | Knowledge & authentication | <b>KA-04</b>             | Historical context update           | Adds or updates information about the object's historical, cultural, or social significance.                                       |
+| <b>PR</b>            | Provenance & rights        | <b>PR-01</b>             | Transfer of ownership               | Documents every change in ownership, specifying the nature of transfer, to build a transparent provenance trail.                   |
+| <b>PR</b>            | Provenance & rights        | <b>PR-02</b>             | Loan & return                       | Records temporary transfers for exhibitions or research, detailing institutions, exhibition titles, periods and returns.           |
+| <b>PR</b>            | Provenance & rights        | <b>PR-03</b>             | Usage rights licensing              | Registers the granting or licensing of rights related to the object's image, reproduction, or commercial use.                      |
+
+**Table B.1 – FLR type**
+
+| <b>Category code</b> | <b>Category</b>          | <b>Sub-category code</b> | <b>Sub-category</b>                  | <b>Description</b>                                                                                                                        |
+|----------------------|--------------------------|--------------------------|--------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>PR</b>            | Provenance & rights      | <b>PR-04</b>             | Official declaration of loss/theft   | Records the formal declaration of loss or theft by the owner or authorities, enabling global alerts and recovery efforts.                 |
+| <b>PR</b>            | Provenance & rights      | <b>PR-05</b>             | Repatriation/restitution             | Records the return of the object to its country, community, or rightful owner as part of the restitution or settlement.                   |
+| <b>EP</b>            | Exhibition & publication | <b>EP-01</b>             | Exhibition history                   | Catalogues all public exhibitions featuring the object, including venues, dates, curators and themes.                                     |
+| <b>EP</b>            | Exhibition & publication | <b>EP-02</b>             | Publication record                   | Lists academic publications, catalogues, articles, or media where the object is featured.                                                 |
+| <b>EP</b>            | Exhibition & publication | <b>EP-03</b>             | Media appearance                     | Documents appearances in mass media, expanding the object's public reach and cultural impact.                                             |
+| <b>OTH</b>           | Other                    | <b>OTH-01</b>            | Unclassified or emerging event types | FLR types that are not included in the above categories. When this category is selected, additional details may be recorded in Table B.2. |
+
+Table B.2 defines an open structure that allows the registration of additional FLR types not listed in Table B.1. Each record represents a FLR type categorized under "other" in Table B.1 and is identified by a unique other\_FLR\_id.
+
+**Table B.2 – Other FLR type**
+
+| <b>Element_name</b> | <b>Data type</b> | <b>Description</b>                                                                                                                                                                                          |
+|---------------------|------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| other_FLR_id        | String           | A unique identifier is assigned to each additional FLR type. The identifier shall follow the format "OFLR-XXXX", where "XXXX" represents a sequential alphanumeric code assigned by the registering system. |
+| other_FLR_type      | String           | Free-text name of an FLR type not represented in Table B.1 (the controlled vocabulary).                                                                                                                     |
+
+NOTE – Table B.2 provides flexibility for CRATS users to record new FLR types not listed in Table B.1.
+
+## Bibliography
+
+- [b-ITU-T F.751.0] Recommendation ITU-T F.751.0 (2020), *Requirements for distributed ledger systems.*
+- [b-ITU-T X.1255] Recommendation ITU-T X.1255 (2013), *Framework for discovery of identity management information.*
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,530 @@
+
+
+Recommendation
+
+**ITU-T F.742 (V2) (03/2025)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+**Service description and requirements for  
+distance learning services**
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white latitude and longitude lines, and the letters 'ITU' in a bold, blue, sans-serif font overlaid on the globe.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.742 (V2)
+
+## Service description and requirements for distance learning services
+
+## Summary
+
+Recommendation ITU-T F.742 (V2) specifies the service description and requirements for distance learning services. Compared to the first edition (2005), this 2025 edition mainly includes the addition of "use cases and scenarios for distance learning service providers", and virtual reality, mixed reality and augmented reality equipment as learner tools. An overall revision is also done, and the content is restructured.
+
+## History \*
+
+| Edition | Recommendation   | Approval   | Study Group | Unique ID          |
+|---------|------------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.742      | 2005-09-13 | 16          | 11.1002/1000/8589  |
+| 2.0     | ITU-T F.742 (V2) | 2025-03-16 | 21          | 11.1002/1000/16250 |
+
+## Keywords
+
+Distance learning, personal learning material database, requirement, use case.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2025
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                        | Page |
+|------------------------------------------------------------------------|------|
+| 1 Scope.....                                                           | 1    |
+| 2 Reference .....                                                      | 1    |
+| 3 Definitions .....                                                    | 1    |
+| 3.1 Terms defined elsewhere .....                                      | 1    |
+| 3.2 Terms defined in this Recommendation.....                          | 1    |
+| 4 Abbreviations and acronyms .....                                     | 2    |
+| 5 Conventions .....                                                    | 2    |
+| 6 Overview.....                                                        | 3    |
+| 7 The reference model of distance learning services.....               | 3    |
+| 8 Use cases and scenarios for distance learning consumers .....        | 4    |
+| 8.1 Real-time interactive distance learning applications.....          | 4    |
+| 8.2 Real-time non-interactive distance learning applications.....      | 6    |
+| 8.3 No-real-time distance learning applications.....                   | 6    |
+| 9 Use cases and scenarios for distance learning service providers..... | 7    |
+| 9.1 Distance learning resources management applications .....          | 7    |
+| 9.2 Distance learning administration management applications .....     | 8    |
+| 10 Requirements .....                                                  | 8    |
+| 10.1 General requirements.....                                         | 8    |
+| 10.2 Requirements for consumers .....                                  | 9    |
+| 10.3 Account requirements.....                                         | 9    |
+| 10.4 Navigation-related requirements .....                             | 10   |
+| 10.5 Synchronization/display-related requirements .....                | 10   |
+| 10.6 Security authentication-related requirements .....                | 10   |
+| 10.7 Authority-related requirements .....                              | 10   |
+| 10.8 Accounting-related requirements .....                             | 10   |
+| 10.9 Quality of service (QoS)-related requirements.....                | 10   |
+| 11 Implementation notes.....                                           | 10   |
+| Bibliography.....                                                      | 11   |
+
+
+
+# Recommendation ITU-T F.742 (V2)
+
+## Service description and requirements for distance learning services
+
+## 1 Scope
+
+This Recommendation specifies the service description and requirements for distance learning services. It is intended to support the multimedia framework for distance learning services [b-ITU-T F.742.2].
+
+## 2 Reference
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 audio-visual multicasting** [b-ITU-T F.741]: When users request the same content at the same time, the audio-visual on-demand services platform lists them in the same multicasting group. The system sends the requested content media streaming to that multicasting group address, then the users within the same group may receive the same requested content.
+
+**3.1.2 audio-visual on-demand** [b-ITU-T F.741]: A kind of network-delivered service that offers the functionality of the home VCR (as play only) without having to get a copy of the chosen material.
+
+**3.1.3 broadcast conference** [b-ITU-T H.323]: A broadcast conference is one in which there is one transmitter of media streams and many receivers. There is no bidirectional transmission of control or media streams. Such conferences may be implemented using network transport multicast facilities, if available.
+
+**3.1.4 broadcast panel conference** [b-ITU-T H.323]: A broadcast panel conference is a combination of a multipoint conference and a broadcast conference. In this conference, several terminals are engaged in a multipoint conference, while many other terminals are only receiving the media streams. There is bidirectional transmission between the terminals in the multipoint portion of the conference and no bidirectional transmission between them and the listening terminals.
+
+**3.1.5 videoconference service** [b-ITU-T F.700]: An audio-visual conference service providing bidirectional realtime-transfer of voice, motion video and real-time text between groups of users in two or more separate locations. Although the audio and motion video information are the essential part of the service, other types of information, such as high resolution still pictures or graphics may also be exchanged.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 distance learning services system (DLSS):** A collection of multimedia service systems with an integrated management system, an integrated authentication, authorization and accounting system to support a part or all kinds of distance learning services.
+
+**3.2.2 individual instruction:** A form of distance learning in which a teacher (or another learner) explains or answers the questions asked by a learner located at a different place through telecommunication networks.
+
+**3.2.3 multi-role learning/team learning:** Learners (of the collective learner entity) who operate as a team on different roles.
+
+**3.2.4 self-paced learning:** A form of distance learning in which learners find a solution to a question given by a teacher, or others, by searching information related to the question from learning resources, analysing the information and giving solutions to the question at their own pace, with or without the help of others.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                   |
+|------|-----------------------------------|
+| AI   | Artificial Intelligence           |
+| AR   | Augmented Reality                 |
+| DLSS | Distance Learning Services System |
+| DRM  | Digital Right Management          |
+| IP   | Internet Protocol                 |
+| MR   | Mixed Reality                     |
+| PC   | Personal Computer                 |
+| PDA  | Personal Digital Assistant        |
+| PPT  | Power Point Presentation          |
+| PSTN | Public Switched Telephone Network |
+| QoS  | Quality of Service                |
+| STU  | Set Top Unit                      |
+| TV   | Television                        |
+| VR   | Virtual Reality                   |
+
+## 5 Conventions
+
+In this Recommendation:
+
+The expression "is required" indicates a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+
+The expression "is recommended" indicates a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance with this Recommendation.
+
+The expression "can optionally" and "may" indicates an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option, and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with this Recommendation.
+
+## 6 Overview
+
+Distance learning involves interactive and non-interactive multimedia communications between learners and learning resources located at two or more separate locations. The aims of learners who use distance learning services may be to obtain some degree certificates based on the degree standards, to receive training given by employers, or to learn special knowledge independently. The distance learning services may be teacher-centred learning services that are similar to traditional physically face-to-face classroom learning, individual instruction, self-paced learning, multi-role learning/team learning, etc.
+
+In the course of distance learning, information may be required from remote databases containing the learning resources, or from live lectures. The material may be textual, aural, graphical, or video in nature and may be stored in a multimedia format. The information can be delivered in point-to-point, point-to-multipoint or multipoint-to-multipoint configuration.
+
+Participants in the distance learning may be located in classrooms equipped with related facilities, offices, homes or other places, such as on trains, where they are able to access a distance learning service system. Learners may learn in real-time with or without interaction with others, following a curriculum schedule or in non-real time by themselves on demand. The equipment that learners use may be a personal computer (PC); personal digital assistant (PDA); mobile phone; virtual reality (VR), mixed reality (MR), augmented reality (AR) equipment; or even a television (TV) set with set top unit (STU). Learners can change their equipment without interruption while they are learning, with the assistance of a distance learning services system (DLSS).
+
+## 7 The reference model of distance learning services
+
+The reference model of distance learning services is shown in Figure 7-1. It is composed of distance learning service providers (DLSS), and consumers/learners. Consumers/learners enrol in a course, a college or a university, acquire learning resources, attend in a virtual class, do and hand in homework, take an exam, etc. through DLSS, while learning service providers may use DLSS to manage, such as provide, create, modify, send or store, learning resources, and use DLSS to administrate, such as create virtual classrooms, arrange curriculum, and manage learning procedures, etc.
+
+The learning resources include live courses given by teachers (visual classes), the digital video recordings of live courses stored in DLSS, courseware produced by courseware creators based on the course materials given by teachers, digital knowledge (visual library, visual laboratory), digital news, etc. The networks which deliver the learning resources among teachers, learners, courseware creators, academic administrators and DLSS may be Internet protocol (IP)-based networks, satellite communication networks, mobile communication networks, public switched telephone network (PSTN), etc.
+
+![Figure 7-1: Reference model of distance learning services. The diagram shows a central rectangular box labeled 'Distance learning services system (DLSS)' connected by lines to two oval shapes on either side. The left oval is labeled 'Distance learning service providers' and the right oval is labeled 'Consumers/ Learners'. Below the diagram, the text 'F.742(V2)(25)' is visible.](0b87abe67b21a93777287649c33e755d_img.jpg)
+
+```
+graph LR; A([Distance learning service providers]) --- B[Distance learning services system (DLSS)]; B --- C([Consumers/ Learners]);
+```
+
+F.742(V2)(25)
+
+Figure 7-1: Reference model of distance learning services. The diagram shows a central rectangular box labeled 'Distance learning services system (DLSS)' connected by lines to two oval shapes on either side. The left oval is labeled 'Distance learning service providers' and the right oval is labeled 'Consumers/ Learners'. Below the diagram, the text 'F.742(V2)(25)' is visible.
+
+**Figure 7-1 – Reference model of distance learning services**
+
+This Recommendation focuses on the use cases and scenario descriptions of distance learning services and requirements for the distance learning service system. The descriptions of the network layer and access layer are outside the scope of this Recommendation.
+
+Teachers and learners both can both utilize the DLSS in the same way during real-time teacher-centred distance learning applications. They can both be consumers/learners of DLSS. In this case, the teacher and learners have similar requirements for the DLSS. This type of user can be defined as the consumer (including learners and teachers).
+
+The teachers, academic administrators or courseware creators deliver the digital form of educational materials and contribute to the distance learning resources. There are users of a DLSS who have the authorization to contribute and update the DLSS's distance resource database with new materials that both teachers and learners can access, such as syllabus design, course setting, course schedule, administration records and student grade records, etc. This type of user is to be defined as the distance learning service provider.
+
+## **8 Use cases and scenarios for distance learning consumers**
+
+### **8.1 Real-time interactive distance learning applications**
+
+#### **8.1.1 Case 1: real-time interactive teaching-centred distance learning**
+
+Real-time interactive teacher-centred distance learning applications are similar to the non-electronic, traditional physically face-to-face classroom education except that the teacher and learners are in different places.
+
+##### **Case implementation**
+
+- The visual classroom establishment
+
+The learners and the teacher receive the curriculum schedule in advance with the assistance of DLSS. Before the lecture begins, the teacher and the learners register to attend the lecture or course on the videoconference service system in DLSS. The videoconference service system sets up a multipoint videoconference environment between the teacher and learners located in two or more locations. If some learners who do not have interactive terminals want to attend the course by only watching the lecture, they can request to attend the lecture by joining the videoconference as receivers only. For them, the environment becomes a broadcast panel conference. Some learners may be students from abroad, from different provinces with different dialects, or unable to hear or understand the audio version of the language used by the teacher. They can request audio to be translated into text and/or appropriate audio in the language they want and have the translated text and/or audio synchronized with the speaker's video shown on their screens.
+
+- The teacher teaching while learners listening
+
+The teacher gives the lecture, and the learners receive the data in either one or other combination of video, audio or text in their respective locations. With the assistance of smart classrooms, in which the teacher gives the lecture, featuring a digital human, the learners may receive and see the teacher, who gives the lecture, in digital human form.
+
+- Question and answer
+
+If a learner in the virtual classroom wishes to ask a question, a request command can be sent to the teacher. If the teacher agrees to the learner's request, the teacher controls the system to let all the other learners see or listen to that particular learner asking the questions and see or hear the teacher's answer. The teacher can ask a learner a question and let the learner answer while the other learners can listen and see the learner and the teacher. After the teacher answers that learner's questions or the teacher wants to continue the lecture, the system can be controlled to return to the teacher-centred mode.
+
+- Learning materials showing
+
+If the teacher wants to show the learners certain material (in text, image, audio or video), the teacher may write it on a blackboard, hold up an image or obtain stored information from audio-visual on-demand service systems, or web-based service systems within the DLSS. At the same time, the learners may get the information from the teacher or obtain it directly from the same learning resources. Learners can see both the teacher and the information on one
+
+screen, or the information can be divided into separate boxes on the same screen, or two different screens could be utilized.
+
+- Quiz questions assignment and answer submission
+
+The teacher may assign quiz questions and allow the learners to submit their answers electronically within a specified period during the course. The teacher can assign different quiz questions to different learners. With the assistance of DLSS, learners can answer the questions by typing the answers on their terminals and then sending to the DLSS, or by answering the questions on papers then scanning and sending the answer sheets to the DLSS. The teacher can see all the learners' answers or see the answer results with the assistance of artificial intelligence (AI) system within the DLSS.
+
+- Course stop
+
+The teacher can stop the lecture, close the videoconference and disconnect the learners.
+
+#### **8.1.2 Case 2: real-time interactive individual instruction**
+
+Real-time interactive individual instruction is similar to traditional physically face-to-face individual instruction except that the person who asks the question and the answerer are located in different locations.
+
+##### **Case implementation**
+
+- Individual instruction between two persons
+
+The learner establishes a connection with the answerer using a videoconference service system within the DLSS. The learner asks the questions, and the answerer responds. If the learner and the answerer use different languages, the DLSS handles translation between them and provides text synchronized with the speaker's video on the screen. During this process, either party may obtain additional information from learning resources using an audio-visual on-demand service system or a web-based service system within the DLSS. The information they obtain may be in different languages, with or without text synchronized with the video. If both want to discuss a single document, they can optionally co-edit the document at the same time using co-editing tools provided by the DLSS. If they are not able to find a solution to the problem, they can invite others to join their discussion by setting up an ad hoc videoconference connection. In this case, it becomes a team learning case. After they finish the discussion, they close the connection(s).
+
+- Individual instruction between a learner and an intelligent machine
+
+For some Q&A cases, when a learner asks questions to the DLSS, the DLSS can optionally answer the learner in text, audio or video by intelligent machine with the assistance of AI.
+
+#### **8.1.3 Case 3: real-time interactive team learning**
+
+This case is similar to the case 1 in clause 8.1.2, except that the interactions are between a team of participants. In this case, a participant may have multiple roles. In other words, a participant's role may be that of an answerer at times, and that of a learner at other times. The communication environment is recommended to be an interactive conference service system, along with an audio-visual on-demand service system and/or a web-based service system within the DLSS. If the learners and the answerer use different languages, the DLSS handles translation between them and provides text synchronized with the speaker's video on the screens. If they want to discuss a single document, they can optionally co-edit one document simultaneously using co-editing tools or the data conference system provided by the DLSS.
+
+### 8.2 Real-time non-interactive distance learning applications
+
+Real-time non-interactive distance learning applications are a form of teacher-centred distance learning. In this situation, the learners and the teacher are located in different places, but the learners are unable to interact with the teacher during the course.
+
+#### Case implementation
+
+- The visual classroom establishment
+
+According to the curriculum schedule, the learners connect with the teacher and receive the course through a broadcast conference service system, or they have joined a broadcasting group to receive the course via an audio-visual multicasting service system. If the learners and the teacher use different languages, the DLSS handles translation between them and provides text synchronized with the speaker's video on the screens.
+
+- The teacher teaching and learning material showing
+
+The teacher teaches as in a traditional physically face-to-face classroom setting, except that there is no interaction between the learners and the teacher. During the course, the teacher may show the learners some information by writing it or retrieving it from learning resources stored in an audio-visual on-demand service system or a web-based service system. The information obtained may be in a different language, with or without text synchronized with the video.
+
+- Exiting course
+
+The teacher ends the course, and the learners are disconnected from the broadcasting videoconference service system and/or exit the broadcasting group of the audio-visual on-demand service system.
+
+### 8.3 No-real-time distance learning applications
+
+Non-real-time distance learning applications include asynchronous, teacher-centred distance learning, individual instruction, team learning, and self-paced learning applications.
+
+#### 8.3.1 Case 1: no-real-time teacher-centred distance learning
+
+When learners cannot attend a class according to the curriculum schedule for various reasons, they may obtain that course using an audio-visual on-demand service system within the DLSS at any time later, if it is stored in a learning resource of the DLSS. In this case, the learner cannot interact with the teacher in real time. However, the learner can submit questions to the web-based service system within the DLSS and receive answers later. The learner can send control commands, such as fast forward, reverse, pause and stop.
+
+##### Case implementation
+
+- Teacher-centred course recorded searching
+
+Learners who want to learn a specific course and have missed it search for the learning resource with the assistance of the navigation system (using of metadata) of an audio-visual on-demand service system within the DLSS. They can choose the language to be used, with or without text synchronized with the video, and can also choose to have sign language support.
+
+- Learner learning by watching streaming course information
+
+After the learner finds the course, the navigation system sends the address of the learning resource where the lecture is stored. The learner receives the multimedia course information and learns by watching the received information. While learning, the learner can send commands such as pause, forward, reverse and stop, on demand.
+
+- Exiting from learning
+
+The course ends, the learner exits the system.
+
+#### **8.3.2 Case 2: no-real-time individual instruction and team learning**
+
+When learners and teachers are not able to or do not want to engage in real-time individual instruction, they can use a bulletin board system (BBS) or e-mail systems for individual instruction and team learning.
+
+Students ask questions by sending them electronically to the teacher or another individual who answers later through the DLSS.
+
+#### **8.3.3 Case 3: no-real-time self-paced**
+
+When a person is seeking a solution to a particular problem or wishes to acquire some special knowledge, they can do so by using an audio-visual on-demand service system, or a web-based system of the DLSS.
+
+Learners can remotely search for learning material in video, still images, text, and audio that they are interested in from learning resource of the DLSS, on demand. Learners learn by watching the recorded materials they select. They can control the delivery (fast forward, reverse, pause and stop) of the content. They can also store the selected material in local storage for later review, if permitted. After finishing learning, learners exit the system.
+
+## **9 Use cases and scenarios for distance learning service providers**
+
+### **9.1 Distance learning resources management applications**
+
+#### **9.1.1 Case 1: distance learning resources creating**
+
+Courseware creators or teachers create courseware by recording live virtual classes, permitted with minor modification based on suggestions from the teachers who give the classes, and then send and store them in the learning resources of DLSS. Teachers or courseware creators make teaching/learning material, such as courseware used in virtual classes, homework used by learners, and teaching reference material (in slide show, file, audio, video, text, etc.) for use by teachers and learners with the assistance of tools within DLSS.
+
+##### **Case implementation**
+
+- A courseware creator accesses a live virtual course, and records the virtual course, permitted in advance, in audio or video during the virtual course. The courseware is processed, a name is added for the recording of the virtual course, and it is uploaded to a suitable place in the learning resource of DLSS.
+- Courseware creators or teachers create courseware, quiz questions, etc. (in slide show, file, video, text, etc.) to be used in classes using the tools provided by DLSS. Teachers upload reference materials (in slide show, files, video, text, etc.) to be used in classes to the learning resources of DLSS.
+
+#### **9.1.2 Case 2: electrical learning resource identification allocation**
+
+Courseware creators allocate identifiers for each learning resource.
+
+Learning resource manager makes the resource identity allocation and identity numbering rules of learning resources. The learning resource manager allocates identifiers to learning resources based on the rules.
+
+#### **9.1.3 Case 3: electrical learning resource navigation**
+
+Courseware creators make an electronic learning resource guide for users.
+
+The learning resource manager creates the presentation methods of learning resource guide to facilitate the users. Users can browse the learning materials by searching keywords or using the learning resource guide.
+
+#### **9.1.4 Case 4: personal learning material database providing**
+
+DLSS creates a customer's personal learning material database.
+
+The customer's historical learning materials, including but not limited to books, courseware learned, homework, etc., or recommends learning references such as reference books, related course guides, etc. based on the customer's interest or application, are collected with the assistance of AI system of DLSS.
+
+### **9.2 Distance learning administration management applications**
+
+#### **9.2.1 Case 1: customer management**
+
+Academic administrators manage teachers' names, subject, timetables, and learners' names, genders, classes and grades in school.
+
+Academic administrators create different user account for different kinds of users (teacher, learner, courseware creator), and assign different authorities to different users. Users fill in their own personal information on their account. Academic administrator manages user timetable, subject, and learning states, etc.
+
+#### **9.2.2 Case 2: curriculum developing**
+
+Academic administrators develop and modify the curriculum.
+
+An academic administrator develops curriculum and prepares different timetables for each learner based on the learner's choices, modifies and notifies the changes to the personal timetable through the DLSS.
+
+#### **9.2.3 Case 3: learner attendance logging**
+
+DLSS logs the customers' and distance learning providers' activities on DLSS, such as attending visual classes. Academic administrators or teachers check the learners who attend the virtual classes or access learning resources.
+
+DLSS takes charge of logging the applications of users, including accessing time, leaving time, accessing classes and learning resource. DLSS authorizes learners to browse their own learning log and authorizes teachers to browse their students' learning log.
+
+#### **9.2.4 Case 4: statistical tables creating**
+
+Academic administrators or teachers produce all kinds of statistical tables such as learner attendance, examination results, learner enrolment statistical tables.
+
+Academic administrators, teachers or learners request statistical tables, such as learner attendance, examination results. The DLSS returns the related statistical tables to the requesters.
+
+## **10 Requirements**
+
+### **10.1 General requirements**
+
+GR-01: A DLSS is required to consist of the functions of at least one of the four systems; a videoconference service system, an audio-visual on-demand- service system, a data conference service system and a web-based service system.
+
+GR-02: A DLSS is recommended to provide uniform authentication and authorization services to end-users and allow users to use related learning materials once they have passed authentication.
+
+GR-03: A DLSS is recommended to provide real-time and/or non-real-time distance learning services.
+
+GR-04: A DLSS is recommended to provide point-to-point, point-to-multipoint and multipoint-to-multipoint services.
+
+GR-05: A DLSS is recommended to provide AI assistance tools, such as courseware creation tools, file editing tools, and statistical table creating tools.
+
+### **10.2 Requirements for consumers**
+
+CR-01: A DLSS is recommended to provide various mechanisms to provide all forms of distance learning services on demand.
+
+CR-02: A DLSS is recommended to enable the provision of distance learning services to special groups of consumers, such as a closed user group of registered students of a university.
+
+CR-03: A DLSS is recommended to allow teachers/learners to access it by using different terminals such as PDA, PC, AR, MR, VR equipment, TV plus STU, and mobile phones.
+
+CR-04: A DLSS is recommended to allow learners to use distance learning services following curriculum schedules, or on demand.
+
+CR-05: A DLSS is recommended to allow learners to reuse learning materials: e.g., by storing learning materials locally, being able to replay them, or sharing them with others for discussion at a designated time.
+
+CR-06: A DLSS is recommended to allow learners to use two or more terminals to view a live lecture and other learning materials or to view a live lecture, other students and other learning materials on the same screen with synchronization.
+
+CR-07: A DLSS is recommended to allow teachers/learners to search curriculum schedules, learning materials and personal information, e.g., user's enrolment and course grade information.
+
+CR-08: A DLSS is recommended to allow teachers/learners to change their terminals while they receive services without obvious interruption of the services; for example, they can change their terminals from PCs to mobile phones.
+
+CR-09: A DLSS is recommended to allow teachers/learners to control non-real-time learning materials on demand, by means of fast forward, reverse, pause and stop.
+
+CR-10: A DLSS is recommended to allow listening-only learners to participate in interactive distance learning courses.
+
+CR-11: A DLSS is recommended to allow learners to pose questions and receive answers from an intelligent machine.
+
+CR-12: A DLSS is recommended to allow learners to choose if they want to use different languages, sign language and text synchronized with video with lip-reading requirements as stipulated in [b-ITU-T H Suppl.1].
+
+### **10.3 Account requirements**
+
+AR-01: A DLSS is recommended to assign a unique account to users and provide different permission controls to different users.
+
+AR-02: A DLSS is recommended to allow users to use a single account to conduct instant messages, group voice/video calls, live streaming, file exchanges and e-mailing across different organizations.
+
+### **10.4 Navigation-related requirements**
+
+NR-01: A DLSS is recommended to provide mechanisms to help users find learning materials or access course schedules.
+
+NR-02: A DLSS is recommended to provide the navigation information including the course name, and the languages which can be provided in audio and text synchronized with the video.
+
+### **10.5 Synchronization/display-related requirements**
+
+SYNR-01: A DLSS is recommended to provide synchronization/display mechanisms to synchronize several live videos or a live video with sign language, text synchronized with the live video, and pre-stored learning materials.
+
+### **10.6 Security authentication-related requirements**
+
+SECR-01: DLSS is recommended to provide security authentication to users, including consumers and distance learning service providers, using their unique identification names.
+
+### **10.7 Authority-related requirements**
+
+AUR-01: The DLSS is recommended to adopt some digital right management (DRM) methods to protect the copyrights of learning resources.
+
+AUR-02: The DLSS is recommended to provide mechanisms to ensure the security of user information and resources.
+
+### **10.8 Accounting-related requirements**
+
+ACR-01: The DLSS is recommended to provide different accounting policies, such as accounting for a closed user group, accounting based on usage duration, or accounting based on the number of courses accessed, based on the different types of applications.
+
+### **10.9 Quality of service (QoS)-related requirements**
+
+QR-01: The DLSS is recommended to provide video and audio information that are clear and free of perceptible asynchrony between audio and video and text.
+
+QR-02: The DLSS is recommended to ensure that text-based learning material displayed on terminals are clearly readable.
+
+QR-03: The DLSS is recommended to ensure that the display learning materials provided in video, audio, text, still image, and handwriting is synchronized on the consumer terminals.
+
+QR-04: The DLSS is recommended to respond to requests for learning material within reasonable time.
+
+## **11 Implementation notes**
+
+Distance learning applications are closely related to videoconferencing, audio-visual on-demand, IPTV and web-based applications, but differ in that their primary purpose is teaching and learning. The information involved relates to learning resources and learning records, and the participants are teachers and learners.
+
+## Bibliography
+
+- [b-[ITU-T F.700](#)] Recommendation ITU-T F.700 (2000), *Framework Recommendation for multimedia services*.
+- [b-[ITU-T F.741](#)] Recommendation ITU-T F.741 (2005), *Service description and requirements for audiovisual on-demand services*.
+- [b-[ITU-T F.742.2](#)] Recommendation ITU-T F.742.2 (2024), *Functional architecture for distance learning services*.
+- [b-[ITU-T H.323](#)] Recommendation ITU-T H.323 (V8) (2022), *Packet-based multimedia communications systems*.
+- [b-[ITU-T H Suppl.1](#)] H-series Recommendations – Supplement 1 (1999), *Application profile – Sign language and lip-reading real-time conversation using low bit-rate video communication*.
+- [b-IEEE 1484.1-2003] IEEE 1484.1-2003, *IEEE Standard for Learning Technology – Learning Technology Systems Architecture (LTSA)*.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+# Recommendation **ITU-T F.742.1 (12/2022)**
+
+SERIES F: Non-telephone telecommunication services  
+Multimedia services
+
+## --- **Requirements for smart class systems based on artificial intelligence**
+
+![ITU logo](390120de4fe440c42fea8154fcaad334_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international teletext service                              | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.742.1
+
+# Requirements for smart class systems based on artificial intelligence
+
+## Summary
+
+Recommendation ITU-T F.742.1 describes application scenarios and requirements for smart class system based on artificial intelligence, including application scenarios, service requirements, management requirements, and security considerations.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.742.1  | 2022-12-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/15184">11.1002/1000/15184</a> |
+
+## Keywords
+
+Artificial intelligence, education, smart class system.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|     |                                                                                       |    |
+|-----|---------------------------------------------------------------------------------------|----|
+| 1   | Scope .....                                                                           | 1  |
+| 2   | References.....                                                                       | 1  |
+| 3   | Definitions .....                                                                     | 1  |
+| 3.1 | Terms defined elsewhere .....                                                         | 1  |
+| 3.2 | Terms defined in this Recommendation .....                                            | 2  |
+| 4   | Abbreviations and acronyms .....                                                      | 2  |
+| 5   | Conventions .....                                                                     | 2  |
+| 6   | Overview of smart class systems based on artificial intelligence .....                | 2  |
+| 7   | Typical application scenarios of smart class systems .....                            | 3  |
+| 7.1 | Intelligent study preparation pre-class .....                                         | 4  |
+| 7.2 | Intelligent lecture preparation pre-class .....                                       | 4  |
+| 7.3 | Learning aid during the class stage .....                                             | 4  |
+| 7.4 | Portrait of learning status in class.....                                             | 4  |
+| 7.5 | Teaching effect analysis after class .....                                            | 5  |
+| 7.6 | Learning effect analysis after class .....                                            | 5  |
+| 8   | Service requirements of smart class systems based on artificial intelligence .....    | 5  |
+| 8.1 | Requirements for class interaction .....                                              | 6  |
+| 8.2 | Requirements for objective analysis.....                                              | 6  |
+| 8.3 | Requirements for intelligent push of course resources .....                           | 7  |
+| 8.4 | Requirements for display of teaching and learning results .....                       | 7  |
+| 8.5 | Requirements for resource generation.....                                             | 7  |
+| 8.6 | Requirements for auxiliary tools .....                                                | 9  |
+| 9   | Management requirements of smart class systems based on artificial intelligence ..... | 9  |
+| 10  | Security considerations .....                                                         | 10 |
+|     | Appendix I – A reference architecture for smart class systems .....                   | 11 |
+|     | Bibliography .....                                                                    | 12 |
+
+
+
+# Recommendation ITU-T F.742.1
+
+# Requirements for smart class systems based on artificial intelligence
+
+## 1 Scope
+
+This Recommendation specifies requirements for smart class systems (SCSs) based on artificial intelligence (AI), which specifically describe the scenarios and requirements.
+
+The scope of this Recommendation includes:
+
+- typical application scenarios;
+- service requirements;
+- management requirements;
+- security considerations.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions, which through reference in this text constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 context** [b-ITU-T Y.2002]: The information that can be used to characterize the environment of a user.
+
+NOTE – Context information may include where the user is, what resources (devices, access points, noise level, bandwidth, etc.,) are near the user, at what time the user is moving, the interaction history between person and objects, etc. According to specific applications, context information can be updated.
+
+**3.1.2 device** [b-ITU-T Y.4000]: With regard to the Internet of things, this is a piece of equipment with the mandatory capabilities of communication and the optional capabilities of sensing, actuation, data capture, data storage and data processing.
+
+**3.1.3 machine learning (ML)** [b-ITU-T Y.3172]: Processes that enable computational systems to understand data and gain knowledge from it without necessarily being explicitly programmed.
+
+**3.1.4 machine learning model** [b-ITU-T Y.3172]: Model created by applying machine learning techniques to data to learn from.
+
+NOTE 1 – A machine learning model is used to generate predictions (e.g., regression, classification, clustering) on new (untrained) data.
+
+NOTE 2 – A machine learning model may be encapsulated in a deployable fashion in the form of a software (e.g., virtual machine, container) or the hardware component (e.g., IoT device).
+
+NOTE 3 – Machine learning techniques include learning algorithms (e.g., learning the function that maps input data attributes to output data).
+
+**3.1.5 machine learning database** [b-ITU-T Y.3174]: A component which stores data related to machine learning in the machine learning overlay.
+
+**3.1.6 speech to text** [b-ITU-T H.862.3]: The process of converting speech input into digital text.
+
+**3.1.7 text to speech** [b-ITU-T H.862.3]: The process of converting digital text input into speech.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following term:
+
+**3.2.1 smart class system (SCS)**: A system including hardware and software that is used to: aid instruction; manage hardware, software and data resources of teaching and learning devices; and analyse teaching effectiveness.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|          |                                              |
+|----------|----------------------------------------------|
+| AI       | Artificial Intelligence                      |
+| AR       | Augmented Reality                            |
+| IMT-2020 | International Mobile Telecommunications-2020 |
+| IoT      | Internet of Things                           |
+| ML       | Machine Learning                             |
+| MR       | Mixed Reality                                |
+| SCS      | Smart Class System                           |
+| STT      | Speech to Text                               |
+| TTS      | Text to Speech                               |
+| TV       | Television                                   |
+| VR       | Virtual Reality                              |
+
+# **5 Conventions**
+
+The following conventions are used in this Recommendation:
+
+- The phrase "**is required to**" indicates a requirement that must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+- The phrase "**is recommended to**" indicates a requirement that is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+- The phrase "**can optionally**" indicates a requirement that is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator or service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+# **6 Overview of smart class systems based on artificial intelligence**
+
+With the application of multimedia and information and communication technologies to traditional methods, the effect and quality of teaching has been improved, but it still faces some problems.
+
+- Existing methods for checking attendance are difficult to meet the actual needs of its management, while occupying class time and affecting teaching efficiency. There is a need for high accuracy and efficient methods for checking attendance to assist class management.
+
+- Low efficiency of teacher lecture preparations. In the traditional way, teachers and students do not interact. Teachers prepare lectures according to syllabus, and students follow textbooks before class. This leads to teachers not being able to know whether students have prepared well. It is also difficult for teachers to gain insight into the weaknesses of student preparations and to carry out targeted educational activities.
+- Cramming method of teaching. In the traditional teaching model, knowledge is taught by teachers through blackboards or multimedia devices and students listen passively during class.
+- Low efficiency of absorption. The information that is shared by teachers through blackboards or multimedia devices is passively received by students during the class. There is a lack of interaction between teachers and students. This force-feeding method cannot stimulate student initiative and creativity.
+- Inefficient analysis of teaching effectiveness. Teachers cannot know what students have captured and retained after class immediately. It is also difficult for teachers to check the study progress of each student in real time.
+- Outdated teaching equipment. Auxiliary teaching equipment plays an important role in class. As time goes by, much teaching equipment cannot keep up with the changing needs of AI.
+
+Therefore, there are still many educational activities that need to be improved. In the era of AI, its integration, along with big data technology, into education has been strengthened. AI, which is at the cutting edge of innovation, is considered as an effective way to help human solve problems. By utilizing advanced teaching equipment, and collecting, and analysing educational data, AI can assist teachers or students in enhancing lecture preparation, as well as improving both methods and effectiveness of teaching at each stage of the class.
+
+SCS is designed to improve lecture preparation, enhance interaction between teachers and students and promote teaching quality. Based on AI technology, SCS is an efficient way to reduce the teaching workload, provide a vivid learning environment, develop teaching abilities and performance of teachers and cultivate individual learning styles of students.
+
+SCS is an intelligent system based on AI, big data, cloud computing, Internet of things (IoT) and other intelligent information technologies and helps construct an intelligent teaching and learning service environment, providing resource services, interactive services and teaching tools.
+
+# 7 Typical application scenarios of smart class systems
+
+SCS promotes the transformation from learning knowledge to generating wisdom by creating a student-centred intelligent learning environment and developing intelligent teaching applications. Firstly, based on the intelligent environment, the intelligent application endows the teaching and learning data with educational significance and becomes valuable teaching and learning information through the collection, aggregation, mining and analysis of teaching and learning data. Through collaborative cognition and processing, the information about teaching and learning is transformed into teaching and learning knowledge. Teaching and learning knowledge can then be flexibly applied in teaching and learning activities, and gradually improve the teaching quality of teachers and the learning quality of students. Finally, promote the development of smart classes dominated by data intelligence and AI.
+
+SCS introduces technology into classes, turns the traditional class into one that is information based, interactive, and meets the students' interest points and personality needs. SCS starts from smart learning and smart teaching at the same time to achieve pre-class preparation, in-class learning and after-class consolidation and promotion. The application scenarios of teaching and learning processes based on SCS can be found in Figure 7-1.
+
+![Figure 7-1: Application scenarios of teaching and learning process based on smart class systems. The diagram shows a central circle labeled 'SCS' surrounded by three concentric rings: 'Learning' (inner), 'Teaching' (middle), and 'Pre-class', 'In-class', and 'After-class' (outer). Six application scenarios are shown in circles around the outer ring, connected by dashed arrows: 'Intelligent study preparation' (Pre-class), 'Intelligent lecture preparation' (Pre-class), 'Learning aid in class' (In-class), 'Portrait of learning status' (In-class), 'Teaching effect analysis' (After-class), and 'Learning effect analysis' (After-class). A small label 'F.742.1(22)' is at the bottom right.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+Figure 7-1: Application scenarios of teaching and learning process based on smart class systems. The diagram shows a central circle labeled 'SCS' surrounded by three concentric rings: 'Learning' (inner), 'Teaching' (middle), and 'Pre-class', 'In-class', and 'After-class' (outer). Six application scenarios are shown in circles around the outer ring, connected by dashed arrows: 'Intelligent study preparation' (Pre-class), 'Intelligent lecture preparation' (Pre-class), 'Learning aid in class' (In-class), 'Portrait of learning status' (In-class), 'Teaching effect analysis' (After-class), and 'Learning effect analysis' (After-class). A small label 'F.742.1(22)' is at the bottom right.
+
+**Figure 7-1 – Application scenarios of teaching and learning process based on smart class systems**
+
+## 7.1 Intelligent study preparation pre-class
+
+SCS provides some contents and tasks that students can learn independently before class and push the resource to students to provide them with space for independent thinking. For example, providing attractive resources, videos and pictures for study courses can stimulate student interest in learning. At the same time, SCS can send pre-class questions to students, and the system will automatically generate data analysis reports based on student learning status. SCS can accurately analyse student learning and recommend relevant consolidation exercises to students based on analysis results, thereby developing teaching strategies.
+
+## 7.2 Intelligent lecture preparation pre-class
+
+SCS intelligently analyses the feedback of student preparation for class and help teachers identify the weaknesses within it, so that teachers can organize teaching centred on student learning. SCS can use the knowledge map to assist teachers to complete the preparation. The system can recommend the same type of information, such as the lesson plan, course explanation and homework, to improve the teaching efficiency of the teacher. The map-based search can also return the desired content more accurately.
+
+## 7.3 Learning aid during the class stage
+
+With the help of SCS, teachers can present vivid and attractive cartoons of knowledge, e.g., physics experiment, chemical change, biological growth. Students can also use optical character recognition technology to extract text information. Furthermore, these text materials are collated into electronic notes by mobile phone or other intelligent terminal devices.
+
+Based on network communication devices, holographic projection technology, as well as light and sound technology, SCS combines real scenes and virtual backgrounds for teaching. An SCS can provide real-time display, lossless transmission of teaching processes, and enable interaction between teachers and students on the same screen when they are in different places.
+
+SCS can help achieve management of teaching resources. When students or teachers are limited by location or time, teachers and students can watch and discuss the courses through SCS.
+
+## 7.4 Portrait of learning status in class
+
+SCS can analyse individual differences among students, e.g., their ability and style of learning, and help improve their abilities depending on student gender, age, grade, habits, etc., and design
+
+personalized learning methods to improve their ability. SCS can also predict student' performance through historical learning data.
+
+## 7.5 Teaching effect analysis after class
+
+After class, teachers can release questions about the class through SCS and guide students to participate in answering questions. Based on this, SCS can help teachers analyse which parts of knowledge are not fully understood by students, evaluate teacher teaching ability, and provide reasonable teaching suggestions.
+
+At the same time, SCS can help teachers analyse the teaching process, take student achievements as labels, analyse the correlation between different teaching methods and knowledge mastery, and recommend different teaching methods to teachers according to different knowledge point.
+
+## 7.6 Learning effect analysis after class
+
+After class, SCS carries out tests to: analyse which parts of knowledge are not fully understood by students; automatically sorts out and summarize the questions on which students make mistakes; and evaluates the learning effect on students. At the same time, with the information collected in class, SCS can evaluate student learning status and help students know their learning level and whether the learning strategies are useful. Based on student historical learning data to generate student portraits, SCS can analyse their levels from qualitative and quantitative perspectives (such as different subjects, different difficulties), and thus propose different reviews, a preview plan, learning suggestions and even occupation planning.
+
+# 8 Service requirements of smart class systems based on artificial intelligence
+
+SCS helps change educational concepts of teachers, reconstructs learning processes of students in and out of class, and promotes student active and personalized learning under the guidance of teachers. Through a new generation of information technology, such as big data and AI, SCS achieves intelligent correction of the results of the work. SCS can run alongside teaching, analyse dynamically and evaluate data diagnostically in the learning process, to form a precise learning analysis report to help teachers understand the learning situation of students or their class. From the perspective of the technical level, SCS includes six major modules: class interaction; objective analysis; intelligent push of course resources; display of teaching and learning results; resource generation; and auxiliary tools. Each module and main technologies are shown in Figure 8-1. This clause provides the general requirements and recommendations for SCS service.
+
+![Diagram of the main technical modules of smart class systems (SCS). The central element is a circular arrow labeled 'SCS'. Six modules are arranged around it: Class interaction, Objective analysis, Intelligent push of course resources, Display of teaching and learning results, Resource generation, and Auxiliary tools. Each module has associated features described in text.](c78c2eefd86269d1740ab85a916f24f2_img.jpg)
+
+The diagram illustrates the main technical modules of smart class systems (SCS). At the center is a circular arrow labeled "SCS". Surrounding this center are six rectangular boxes, each representing a module. Clockwise from the top, the modules and their associated features are:
+
+- Class interaction**: Answer race, random selection, specify an answer
+- Objective analysis**: Single-choice questions, multiple-choice questions, blank filling questions, true-false questions, short answer questions
+- Intelligent push of course resources**: Uploading and downloading of pictures, real-time video display
+- Display of teaching and learning results**: Display diverse works, learning results of individuals or groups, highlight the learning results
+- Resource generation**: Record resources in the process of teaching and learning, conduct course review
+- Auxiliary tools**: Auxiliary teaching devices, automatic adjustment table and chair, recording devices, timer
+
+F.742.1(22)
+
+Diagram of the main technical modules of smart class systems (SCS). The central element is a circular arrow labeled 'SCS'. Six modules are arranged around it: Class interaction, Objective analysis, Intelligent push of course resources, Display of teaching and learning results, Resource generation, and Auxiliary tools. Each module has associated features described in text.
+
+**Figure 8-1 – Main technical modules of smart class systems**
+
+## 8.1 Requirements for class interaction
+
+Participation in a class aims to build a harmonious and democratic atmosphere through the interaction of teachers, students and teaching equipment, so that all levels of learners in the classroom can be actively involved in curriculum-related learning events. The requirements and recommendations for class interaction are as follows.
+
+- SCS is recommended to support multiple ways of class interaction through different question-answer strategies. Based on the teaching situation, teachers can adopt an appropriate classroom interactive strategy to effectively regulate student participation in the class.
+- SCS is recommended for the recognition of blackboard writing by teachers and student handwriting, and suggestions for learning or teaching.
+- SCS is recommended to support interaction through a variety of terminal devices such as: personal computers; pads; mobile phones; television (TV); virtual reality (VR) augmented reality (AR) or mixed reality (MR) equipment; and holographic equipment.
+- SCS is recommended to provide real time, reliable and user-friendly speech-to-text (STT) and text-to-speech (TTS) services by utilizing natural language processing. STT and TTS help communication between students and teachers.
+- STT and TTS are recommended to be editable and automatic error correction.
+
+## 8.2 Requirements for objective analysis
+
+The purpose of objective analysis is to examine student mastery of knowledge and understand the teaching situation of teachers. The requirements and recommendations for objective analysis are as follows.
+
+- SCS is recommended to support the analysis of student preparation for class, identify student weaknesses in knowledge (misunderstanding, beyond comprehension, etc.,) and provide teachers with reasonable lecture preparation suggestions.
+- SCS is recommended to design single- and multiple-choice questions to help teachers examine student mastery of the class.
+- By analysing the knowledge contained in each option, SCS is recommended to assist teachers to understand the learning situation of students, and provide support for effectively promoting the cooperation of learning groups.
+- Through the overall answer, SCS is recommended to help teachers determine student completion of the corresponding problems (such as how many students are participating in learning) and mastery of the course (such as the learning effectiveness of the students).
+- SCS can optionally provide questions of the "fill in the blank", true-false and short answer types. For these kinds of questions, SCS can optionally handle student feedback in vocal form, pictures and text, and SCS can optionally provide teachers with an evaluation of student answers.
+- SCS is recommended to grade examination papers and work results, analyse results after class and form a precise learning analysis report to help teachers understand the learning situation of students or class.
+- SCS is recommended to automatically identify and summarize the questions where students make mistakes.
+- SCS is recommended to utilize an AI algorithm to help students set an individual learning plan or training performance model to predict their future learning situation based on fundamental data, learning data and other characteristic dimensions.
+- SCS is recommended to support the analysis of teacher preparation for class, identify weaknesses in teaching and provide reasonable teaching materials, as well as lecture preparation suggestions.
+
+## **8.3 Requirements for intelligent push of course resources**
+
+SCS assists teachers and students to pass on course resources intelligently. It mainly includes intelligent push methods such as uploading and downloading of pictures, as well as real-time video display. The requirements and recommendations for intelligent push of course resources are as follows.
+
+- SCS is recommended to recognize educational materials, evaluating their level and recommend them to appropriate students.
+- SCS is recommended to support the following four intelligent course resources push strategies:
+  - Teachers and students can send homework or submit works through one click.
+  - Generate the teaching and learning resources by taking pictures or recording through the learning terminal.
+  - The student learning process or effectiveness are presented through taking pictures, and evidence collection, presentation and discussion of results with typical characteristics.
+  - In the process of teaching, teachers can present and share specific teaching sessions or learning results through videos.
+- SCS is recommended to build a personalized knowledge map based on the actual situation of each student, and rely on the construction of the knowledge map to push personalized exercise questions for each student, reduce the time spent on repetitive and invalid questions, and improve learning efficiency.
+- SCS is recommended to support the search function by entering audio, image, video or text of educational materials and specific text, image or video is returned.
+
+## **8.4 Requirements for display of teaching and learning results**
+
+SCS displays diverse works showing the results of student lessons or discussions. SCS helps teachers to comprehensively and quickly understand in a timely fashion the learning process, knowledge internalization and learning results of all students, and provide data support to optimize and adjust teaching strategies.
+
+The requirements and recommendations for display of teaching and learning results are as follows.
+
+- SCS is recommended to analyse the learning results of individuals or groups, including the display of different types of results to expand student thinking. By selecting representative student work, the advantages and deficiencies of SCS can be analysed to promote teaching and learning.
+- SCS is recommended to highlight learning results according to level. SCS is recommended to support the following three highlight strategies.
+  - Highlight excellent results pre-set by teachers, make full use of their demonstration role, and let students understand the typical characteristics of such achievements.
+  - Highlight creative and characteristic achievements and guide students to expand their thinking.
+  - Pay attention to imperfect results, and analyse the reasons for work that is not well completed, to help students to cover learning gaps in a better way.
+
+## **8.5 Requirements for resource generation**
+
+SCS generates teaching resources through one click. It can automatically record resources in the process of teaching and learning in the form of pictures, PDF manuscripts or videos (mainly graphic materials or operation videos displayed on a teacher's screen). SCS is recommended to realize the following three purposes through resource generation:
+
+- help students conduct course review after class;
+- enable students to use resources for personalized tutoring;
+- assist teachers to build a teaching process library, and provide effective materials for the construction of education and teaching resources.
+
+The requirements and recommendations for resource generation are given in clauses 8.5.1 to 8.5.4.
+
+#### **8.5.1 Requirements for data preparation**
+
+The requirements and recommendations for data preparation are as follows:
+
+- SCS is recommended to provide electronic textbooks and materials such as audio, image, video and text;
+- SCS can optionally provide teaching materials such as: VR, AR or MR content; holographic content; flash animation; stickers; music and sound;
+- SCS can optionally provide curriculum information and scheduling, as well as student and teacher attendance information;
+- SCS can optionally provide recording information of teacher lectures, blackboard writing and multimedia teaching;
+- SCS can optionally provide live broadcast and on-demand lecture resources;
+- SCS can optionally provide the knowledge map of data on student learning, teacher teaching and curriculum;
+- SCS is recommended to provide storage space for building machine-learning (ML) databases to store data including audio, images, video, text and knowledge maps.
+
+NOTE 1 – Educational materials can be uploaded and downloaded through different protocols.
+
+NOTE 2 – The SCS data can be opened and shared to ML services and can be accessed only in the SCS. Specification of mechanisms for SCS data openness lie outside the scope of this Recommendation.
+
+#### **8.5.2 Requirements for data pre-processing**
+
+The requirements and recommendations for data pre-processing are as follows:
+
+- SCS is recommended to support the intelligent collection of curriculum resource data in multiple scenarios and multiple teaching modes;
+- SCS is required to support the pre-processing of education materials, such as separating teaching video into frames and extracting key frames;
+- SCS is required to support the recognition and classification of educational videos;
+- SCS is recommended to support multi-dimensional analysis of educational video, including subjects, scenes, objects, labels, voices, text and faces;
+- SCS is recommended to support statistical functions and provide visualized control systems, which can present class conditions through dynamic statistics.
+
+#### **8.5.3 Requirements for model training and deployment**
+
+The requirements and recommendations for model training and deployment are as follows:
+
+- SCS is recommended to support the training of ML models based on an educational ML database;
+- SCS is recommended to support the indication of ML model-training status;
+- SCS is recommended to support the deployment and inference of ML model.
+
+#### **8.5.4 Requirements for data security**
+
+The requirements and recommendations for data security are as follows:
+
+- SCS is required to provide a security and personally identifiable information protection mechanism on collected data;
+- SCS is required to authorize and authenticate access to class data;
+- SCS is required to authorize and authenticate when training and deploying AI capabilities.
+
+### **8.6 Requirements for auxiliary tools**
+
+The requirements and recommendations for auxiliary tools are given in clauses 8.6.1 to 8.6.5.
+
+#### **8.6.1 Requirements for course auxiliary devices**
+
+- SCS is recommended to provide course auxiliary devices for teaching and learning, such as an intelligent timer, intelligent screen and intelligent dictionary pen. The auxiliary devices provide teachers and students with assistance for teaching and learning.
+- Course auxiliary devices of SCS can optionally provide teachers and students with VR, AR or MR and holographic interactive services.
+
+#### **8.6.2 Requirements for recording devices**
+
+- SCS lecture-recording devices (voice recorder, camera, etc.) can optionally acquire data from teacher and student blackboard writing, voices and videos on the premise of ensuring data security.
+
+#### **8.6.3 Requirements for smart tables and chairs**
+
+- SCS is recommended to provide tables and chairs that are flexible to move and can automatically adjust height and tilt angle according to student's height, body mass or sitting position.
+
+#### **8.6.4 Requirements for classroom environment**
+
+- SCS is recommended to automatically adjust temperature, humidity, brightness and other classroom conditions to enhance learning and teaching effects.
+
+#### **8.6.5 Requirements for compatibility**
+
+- SCS is required to support the access by various terminal hardware devices, e.g., a PC; pad; mobile phone; TV; VR, AR or MR equipment and holographic equipment.
+- SCS is recommended to support various operating system platforms.
+- SCS is recommended to be compatible with various browsers.
+
+# **9 Management requirements of smart class systems based on artificial intelligence**
+
+- SCS is recommended to check attendance through face recognition technology, and complete statistics of student attendance results before teaching starts.
+- SCS is recommended to support enquiry into attendance data of students and courses.
+- SCS is recommended to support multi-dimensional data analysis based on departmental or class attendance data.
+- SCS is required to support the management of basic information about teachers and students, including its creation, deletion, modification, searching and browsing, and specify the operation permissions for this function.
+- SCS is required to analyse and display education management information, such as the number of teachers and students, and shows the current teaching progress.
+- SCS is recommended to intelligently generate management suggestions or guidance for education management.
+
+## **10 Security considerations**
+
+This Recommendation describes requirements for SCSs based on AI supported by IMT-2020 and beyond; therefore, general security requirements and mechanisms specified for Internet protocol-based networks and a high-level architecture framework for ML should be applied, see [b-ITU-T Y.3101] and [b-ITU-T Y.3172]. The security mechanisms such as authentication, authority, accounting and encryption should be adopted to ensure SCS security.
+
+## Appendix I
+
+### A reference architecture for smart class systems
+
+(This appendix does not form an integral part of this Recommendation.)
+
+SCS is an intelligent system based on AI, big data, cloud computing, IoT and other intelligent information technologies. It is mainly composed of smart cloud service, a smart platform, smart teaching, learning and management terminal and smart environment terminal. A reference architecture for SCS is depicted in Figure I.1.
+
+- Smart cloud services provide resource management, micro-course management, open courses, online teaching and learning, and online research, etc., based on cloud service.
+- The smart platform is equipped with intelligent centres for classroom communication, data, control and competence.
+- Smart terminals include intelligent teaching, learning and management terminals, such as the teacher's intelligent terminal, the students' intelligent terminal, intelligent management terminals and the parents' intelligent terminal.
+- Smart environment terminals mainly include intelligent hardware facilities and intelligent software equipment. SCS constructs an intelligent teaching and learning service environment, providing resource services, interactive services and teaching tools.
+
+![Reference architecture for smart class systems diagram](33a8f3f01dfa8bce75d23017855a13c5_img.jpg)
+
+The diagram illustrates the reference architecture for smart class systems, organized into three horizontal layers connected by double-headed arrows.
+
+- Top Layer: Smart cloud service** (represented by a cloud icon). It contains six functional blocks: Resource management, Microlecture management, Open course, Online learning, Online teaching, and Online researching.
+- Middle Layer:** Consists of two main components connected by a horizontal double-headed arrow.
+  - Smart platform** (represented by a monitor icon). It includes four centres: Communication centre, Data centre, Control centre, and Competence centre. Below these are four supporting functions: Intelligent algorithm Storage, Search centre Data analysis, Intelligent communication Knowledge base.
+  - Smart environment terminal** (represented by icons of a laptop, tablet, and smartphone). It includes two components: Intelligent hardware and Intelligent software.
+- Bottom Layer: Smart teaching, learning and management terminal** (enclosed in a dashed box). It contains four intelligent terminals connected sequentially by horizontal double-headed arrows:
+  - Teachers' intelligent terminal**: Microlecture, Interaction, Recording, Evaluation.
+  - Students' intelligent terminal**: Microlecture, Interaction, Notes, Evaluation.
+  - Intelligent management terminal**: Teaching effect evaluation, Learning effect evaluation.
+  - Parents' intelligent terminal**: Communication between family and school, Exchange experience.
+
+Reference architecture for smart class systems diagram
+
+F.742.1(22)
+
+**Figure I.1 – Reference architecture for smart class systems**
+
+SCS is designed to improve lecture preparation, enhance interaction between teachers and students and promote teaching quality. Based on AI technology, SCS is an efficient way to reduce the teaching workload, provide a vivid learning environment, develop teaching abilities and performance, and cultivate individual learning styles of students.
+
+## Bibliography
+
+- [b-ITU-T H.862.3] Recommendation ITU-T H.862.3 (2020), *Requirements of the voice management interface for human-care services.*
+- [b-ITU-T Y.2002] Recommendation ITU-T Y.2002 (2009), *Overview of ubiquitous networking and of its support in NGN.*
+- [b-ITU-T Y.3101] Recommendation ITU-T Y.3101 (2018), *Requirements of the IMT-2020 network.*
+- [b-ITU-T Y.3172] Recommendation ITU-T Y.3172 (2019), *Architectural framework for machine learning in future networks including IMT-2020.*
+- [b-ITU-T Y.3174] Recommendation ITU-T Y.3174 (2020), *Framework for data handling to enable machine learning in future networks including IMT-2020.*
+- [b-ITU-T Y.4000] Recommendation ITU-T Y.4000/Y.2060 (2012), *Overview of the Internet of things.*
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.742.2-202401-I_PDF-E/raw.md

@@ -0,0 +1,380 @@
+
+
+# Recommendation **ITU-T F.742.2 (01/2024)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+## --- **Functional architecture for distance learning services**
+
+![ITU logo](6ed175c791b5e156d9c98a8dbcc3318c_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white grid lines and the letters 'ITU' in a bold, blue, sans-serif font.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.742.2
+
+# Functional architecture for distance learning services
+
+## Summary
+
+Recommendation ITU-T F.742.2 specifies the functional architecture for distance learning services.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.742.2  | 2024-01-13 | 16          | 11.1002/1000/15760 |
+
+## Keywords
+
+Collaboration, distant learning, intelligent analysis, massive online course.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2024
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                   | Page |
+|-------------------------------------------------------------------|------|
+| 1 Scope.....                                                      | 1    |
+| 2 References.....                                                 | 1    |
+| 3 Definitions .....                                               | 1    |
+| 3.1 Terms defined elsewhere .....                                 | 1    |
+| 3.2 Terms defined in this Recommendation.....                     | 1    |
+| 4 Abbreviations and acronyms .....                                | 1    |
+| 5 Conventions .....                                               | 1    |
+| 6 Overview.....                                                   | 2    |
+| 7 Functional architecture .....                                   | 2    |
+| 8 Functional entities.....                                        | 3    |
+| 8.1 Real-time interactive distance learning applications .....    | 3    |
+| 8.2 Non-real-time distance learning applications .....            | 4    |
+| 8.3 Learning management application .....                         | 4    |
+| 8.4 Real-time non-interactive distance learning applications..... | 4    |
+| 8.5 Authentication and authorization .....                        | 5    |
+| 8.6 User management .....                                         | 5    |
+| 8.7 Resource management.....                                      | 5    |
+| 8.8 Multimedia control .....                                      | 5    |
+| 9 Reference points .....                                          | 5    |
+| 10 Information flow .....                                         | 6    |
+| 10.1 User accesses learning resource .....                        | 6    |
+| 10.2 User contributes content to learning resource .....          | 6    |
+| Bibliography.....                                                 | 7    |
+
+
+
+# Recommendation ITU-T F.742.2
+
+## Functional architecture for distance learning services
+
+## 1 Scope
+
+This Recommendation specifies a functional architecture for distance learning services.
+
+The scope of this Recommendation includes:
+
+- Functional architecture for distance learning services, including specification of capability sets, functional entities and reference points.
+- Information flow for distance learning services, including user management, service interaction, etc.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation
+
+None.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 resource** [b-IETF RFC 3986]: This specification does not limit the scope of what might be a resource; rather, the term "resource" is used in a general sense for whatever might be identified by a uniform resource identifier (URI).
+
+### 3.2 Terms defined in this Recommendation
+
+None.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+ICT Information and Communication Technology
+
+ID Identifier
+
+URI Uniform Resource Identifier
+
+## 5 Conventions
+
+In this Recommendation, the following conventions apply.
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+- The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Overview
+
+Distance learning services use information and communication technologies (ICTs) for education delivery. With the support of networks, learning can be anywhere, anytime. With the facilitation of cloud computing, education can be multimedia enabled, customized and widely shared, and third parties can actively participate in the activities for education content provision and software development based on distance learning ICT infrastructures.
+
+Distance learning is beneficial for remote locations where educational resources are relatively scarce.
+
+The use of distance learning is also vitally important as it helps prevent contagious diseases from spreading in schools and training institutes during pandemic times.
+
+Distance learning services are composed of audio, video and message communication. Besides that, they also include service features like screen sharing. Aside from communication between human beings, it also allows users to interact with learning programs and digital learning content.
+
+Also, apps and content feed to distance learning may come from different suppliers, applicable to different age levels. Thus, user management and third-party management are required to be specified to meet the operational requirements.
+
+The architectural design of distance learning system should consider supporting all the features mentioned above.
+
+Regarding the scalability of distance learning services, from a virtual classroom that supports dozens of students to a very large-scale online lecture that accommodates thousands of students, the architectural design is quite different, and a different network infrastructure is required.
+
+## 7 Functional architecture
+
+Figure 7-1 shows the functional architecture for distance learning.
+
+![Functional architecture for distance learning diagram showing four layers: Application, Control, Resource, and User, connected by interfaces IF1, IF2, IF3, IF4, and IF5 through a central Network cloud.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+The diagram illustrates the functional architecture for distance learning, organized into four layers separated by interfaces (IF1, IF2, IF3, IF4, IF5) and a central Network cloud.
+
+- Application layer:** Contains five modules: Learning management application, Real-time interactive distance learning applications, Real-time non-interactive distance learning applications, Non-real-time distance learning applications, and Business and institutional applications.
+- Control layer:** Contains four modules: Authentication and authorization, Resource manager, Multimedia control, and User manager.
+- Resource layer:** Contains two modules: Learning resources repository and Third party resource.
+- User layer:** Contains three modules: Distance learning service provider, Consumer/learner, and Guardian.
+
+Interfaces and connections:
+
+- IF1:** Connects the User layer to the Network cloud.
+- IF2:** Connects the Application layer to the Control layer.
+- IF3:** Connects the Control layer to the Resource layer.
+- IF4:** Connects the Control layer to the Network cloud.
+- IF5:** Connects the Control layer to the Network cloud.
+
+F.742.2(24)
+
+Functional architecture for distance learning diagram showing four layers: Application, Control, Resource, and User, connected by interfaces IF1, IF2, IF3, IF4, and IF5 through a central Network cloud.
+
+**Figure 7-1 – Functional architecture for distance learning**
+
+The functional capabilities of the layers in the distance learning architecture are as follows:
+
+- **Application layer:** The application layer contains five modules, which include real-time interactive distance learning applications, real-time non-interactive distance learning applications, non-real-time distance learning applications, business/institutional applications, and learning management applications. These modules provide several applications for distance learners, educators and guardians, such as virtual classrooms, online quizzes, group discussion, lecture broadcasting, attendance check, homework assignment and exam grading.
+- **Control layer:** The control layer contains four modules, which include user management, authentication and authorization, resource management, and multimedia control. These modules provide several functions such as instant message, address book, video call, cloud storage management and third-party open platform.
+- **Resource layer:** learning resource repository and third-party resource, for example as specified in [b-IETF RFC 3986], provide educational content for the functional layer.
+- **User layer:** The user layer contains distance learning service providers, consumers/learners, and guardians.
+
+## 8 Functional entities
+
+### 8.1 Real-time interactive distance learning applications
+
+In order to provide real-time virtual distance learning services for the users, this module should have the following functions:
+
+RIDL-01: Provide a platform where educators can share their knowledge with learners via video or audio meeting room, web pages and other kinds of digital form educational material.
+
+RIDL-02: Provide a platform that allows users to communicate via instant messages, text messages, group voice/video calls, live streaming and file exchanges across different organizations.
+
+RIDL-03: Provide a platform to set up and manage online screen sharing, digital whiteboarding, attendance register, real-time co-annotation, and polling for the virtual or hybrid classroom.
+
+### **8.2 Non-real-time distance learning applications**
+
+In order to provide non real-time distance learning services for the learner, the module should have the following functions:
+
+NRDL-01: Provide a platform where educators can share their knowledge with learners via e-books, recorded video files, web pages and other kinds of digital form educational material.
+
+NRDL-02: Provide a unified platform that allows users to communicate via text messages, forum, bulletin boards, file exchanges and e-mailing across different organizations.
+
+NRDL-03: Provide a function where the learner could submit their assignment and complete examinations or quizzes.
+
+NRDL-04: Provide a function for educators and guardians to view the learners' exam scores.
+
+NRDL-05: Provide a platform to manage and push notifications and announcements within the school or across different organizations, for example, between the Department of education and schools.
+
+### **8.3 Learning management application**
+
+In order to manage education services by the educator and learner, the module should have the following functions:
+
+LM-01: Provide a function to develop curricula, such as syllabus design, course setting, course schedule and learning materials preparation.
+
+LM-02: Provide a function for creating online assignments and tracking study progress.
+
+LM-03: Provide a tool for creating quizzes and exams from the question repository which can be reused in different quizzes.
+
+LM-04: Provide a tool for sharing or uploading course materials like syllabus, reference files or class rules.
+
+LM-05: Provide a personalized dashboard for learners to establish their personal study tracking, course enrolment and view exam scores.
+
+LM-06: Provide a tool for the educator to distribute quizzes, exams or assignments to the selected learners from the resource repository.
+
+LM-07: Provide a grading tool for the educator to grade an assignment or exam, and for leaving personalized feedback for each assignment or exam.
+
+LM-08: Provide a tool for educators to review selected learners' statistical performance using graphic display.
+
+### **8.4 Real-time non-interactive distance learning applications**
+
+In order to provide real-time non-interactive distance learning services for the users, the communication service should have the following functions:
+
+RNDL-01: Provide a platform that allows users to conduct live streaming, file exchanges and e-mailing across different organizations.
+
+### **8.5 Authentication and authorization**
+
+In order to provide authentication and authorization functions for resource management and user management, this module should have the following functions:
+
+AA-01: Provide the access control mechanism to user management and third party authentication.
+
+AA-02: Provide the authorization for third party resources and learning resource repository via resource management.
+
+AA-03: Provide a mechanism to manage the log.
+
+### **8.6 User management**
+
+User management provides management of learners' and educators' profiles. It should have the following functions:
+
+UM-01: Provide permission control to set privileges for different users.
+
+UM-02: Provide user profile management that includes the following profile content:
+
+- User role: educator, student or guardian (father or mother);
+- User information: name, gender and user ID;
+- Educational information: campus, period (kindergarten, primary school, middle school, high school), grade and class ID.
+
+### **8.7 Resource management**
+
+In order to manage the resource from the learning resource repository and third party resources, this module should have the following functions:
+
+RM-01: Manage the educational resource within the learning resource repository and third party resources, such as searching, browsing, uploading, deleting, editing and downloading educational content.
+
+RM-02: Provide a function for third party organizations to develop more educational applications, contents and functionalities.
+
+### **8.8 Multimedia control**
+
+In order to provide the multimedia control function for the application layer, this module should have the following function:
+
+MC-01: Provide multimedia capabilities, such as group voice/video conference, online group communication, online screen sharing, online streaming, session recording, file downloading/uploading and file sharing.
+
+## **9 Reference points**
+
+A description of reference points for distance learning, as shown in Figure 7-1, is provided below:
+
+IF1: Interface 1 supports communication between the user layer and the control layer. It enables the user to interact with service modules to utilize various education services.
+
+IF2: Interface 2 supports communication between the application layer and the control layer. It enables the functional layer's modules to provide essential functions for the control layer.
+
+IF3: Interface 3 supports communication between the control layer and the resource layer. It enables the functional layer to access the resources both within and outside the organization.
+
+IF4: Interface 4 is used to receive the access request from user management and provide access to user management.
+
+IF5: Interface 5 is used to provide resource authorization for the resource management function.
+
+## **10 Information flow**
+
+### **10.1 User accesses learning resource**
+
+Step 1: The learner or educator accesses the learning service function in the control layer as a user via IF1.
+
+Step 2: The learning service function requests the educational material from the resource management function via IF2.
+
+Step 3: The resource management function ingests the designated educational material from the learning resource repository via IF3 and establishes access to the user.
+
+### **10.2 User contributes content to learning resource**
+
+Step 1: The educator accesses the learning management service function in the service layer as a user via IF1 to request an educational material upload.
+
+Step 2: The resource management function allocates the educational material via IF3 in the learning resource repository and returns the result to the learning management service function.
+
+## Bibliography
+
+[b-IETF RFC 3986] IETF RFC 3986 (2005), *Uniform Resource Identifier (URI): Generic Syntax*.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,428 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.12**
+
+(06/2021)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for edge computing in video  
+surveillance**
+
+Recommendation ITU-T F.743.12
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in white, bold, sans-serif font superimposed on the globe.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## Recommendation ITU-T F.743.12
+
+# Requirements for edge computing in video surveillance
+
+## Summary
+
+Recommendation ITU-T F.743.12 defines the requirements for edge computing in video surveillance. Edge computing is a distributed computing paradigm aimed at providing various computing services at the edge of the network, and it brings computation and data storage closer to the data source or the location where it is needed, to improve response time and save bandwidth. By using the edge computing technology, the video surveillance system can perform intelligent video analysis and store data near the network premises units. And the edge computing platform provides the management capabilities of the edge resources and functional components to the video surveillance system. It can improve the video processing efficiency and quality of services and reduce the infrastructure cost of the video surveillance system. This Recommendation describes the application scenarios and requirements for edge computing in the video surveillance system.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.12 | 2021-06-13 | 16          | <a href="http://handle.itu.int/11.1002/1000/14680">11.1002/1000/14680</a> |
+
+## Keywords
+
+Edge computing, requirements, scenarios, video surveillance.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2021
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|     |                                                                                                        |   |
+|-----|--------------------------------------------------------------------------------------------------------|---|
+| 1   | Scope .....                                                                                            | 1 |
+| 2   | References.....                                                                                        | 1 |
+| 3   | Definitions .....                                                                                      | 1 |
+| 3.1 | Terms defined elsewhere .....                                                                          | 1 |
+| 3.2 | Terms defined in this Recommendation.....                                                              | 1 |
+| 4   | Abbreviations and acronyms .....                                                                       | 2 |
+| 5   | Conventions .....                                                                                      | 2 |
+| 6   | Scenarios.....                                                                                         | 2 |
+| 6.1 | Video analysis based on edge computing servers .....                                                   | 2 |
+| 6.2 | Collaborative computing based on intelligent premises units (IPUs) and<br>edge computing servers ..... | 3 |
+| 6.3 | Collaborative edge-cloud computing .....                                                               | 3 |
+| 6.4 | Regional PU/IPU management based on edge computing servers .....                                       | 4 |
+| 6.5 | Video storage.....                                                                                     | 4 |
+| 6.6 | Resource, task, and algorithm management.....                                                          | 4 |
+| 7   | Requirements for edge computing in video surveillance .....                                            | 4 |
+| 7.1 | User requirements.....                                                                                 | 4 |
+| 7.2 | Service requirements .....                                                                             | 5 |
+| 7.3 | Security requirements .....                                                                            | 6 |
+| 7.4 | Management requirements .....                                                                          | 7 |
+| 7.5 | Scalability requirements .....                                                                         | 8 |
+| 7.6 | Reliability requirements .....                                                                         | 8 |
+| 7.7 | Performance requirements.....                                                                          | 8 |
+|     | Bibliography.....                                                                                      | 9 |
+
+
+
+# Requirements for edge computing in video surveillance
+
+# 1 Scope
+
+Edge computing technology can support efficient video processing and storage at the network edge of the video surveillance system, to improve the quality of services and reduce the infrastructure cost. This Recommendation describes the application scenarios and requirements for edge computing in the video surveillance system.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions, which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 application** [b-ITU-T Y.101]: A structured set of capabilities, which provide value-added functionality supported by one or more services.
+
+**3.1.2 customer unit** [b-ITU-T H.626V2]: A device located at the customer part of a video surveillance system and used to present multimedia information (such as audio, video, image, alarm signal, etc.) to the end user.
+
+**3.1.3 premises unit** [b-ITU-T H.626V2]: A device located at the remote part of a video surveillance system and used to capture multimedia information (such as audio, video, image, alarm signal, etc.) from a surveilled object.
+
+**3.1.4 service** [b-ITU-T Y.101]: A structure set of capabilities intended to support applications.
+
+**3.1.5 video surveillance system** [b-ITU-T H.626V2]: A telecommunication service focusing on video (including audio and image) application technology, which is used to remotely capture multimedia (such as audio, video, image, alarm signal, etc.) and present them to the end user in a user-friendly manner, based on a managed broadband network with ensured quality, security and reliability.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 edge computing platform supporting video surveillance**: A geographically distributed computing paradigm, in which various servers at the edge of the network are ubiquitously networked to collaboratively provide the elastic computation, communication, and storage services to video surveillance applications. By constructing the edge computing layer between the premises units and the remote video surveillance centre, the multimedia data can be processed and stored in the
+
+networked edge servers, which is close to the data sources. It can also effectively meet the demands of real-time or latency-sensitive video surveillance applications, and notably ease the network bandwidth bottleneck, in comparison with the centralized computing paradigm.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                                       |
+|-------|-------------------------------------------------------|
+| CU    | Customer Unit                                         |
+| ECPVS | Edge Computing Platform supporting Video Surveillance |
+| IPU   | Intelligent Premises Unit                             |
+| IVS   | Intelligent Video Surveillance                        |
+| PTZ   | Pan/Tilt/Zoom                                         |
+| PU    | Premises Unit                                         |
+| VS    | Video Surveillance                                    |
+
+# **5 Conventions**
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement that must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement that is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+# **6 Scenarios**
+
+This clause describes the various scenarios for edge computing in video surveillance (VS).
+
+## **6.1 Video analysis based on edge computing servers**
+
+### **Case 1: Traffic flow analysis**
+
+The intelligent video surveillance (IVS) system can be used by the traffic department for monitoring the traffic flow situation. The traffic flow analysis function component is deployed in the edge computing servers for the IVS system. When a traffic administrator needs to obtain the traffic flow situation of some key road sections, they can configure the traffic flow analysis function of the related regional edge servers to process the related surveillance video streams.
+
+Step 1: The user logs into the IVS system through the customer unit (CU), chooses some premises units (PUs) which are deployed at the interested key road sections and configures the traffic flow analysis function. They then submit the traffic flow analysis request to the IVS system.
+
+Step 2: After receiving the request, the IVS system authenticates the user information, and configures the traffic flow analysis function of the corresponding edge computing servers. The IVS system then responds to the CU with the information of the traffic flow analysis function.
+
+Step 3: The edge servers pull the video streams from the corresponding PUs, perform the traffic flow analysis function online, and then sends the analysis results to the IVS system which are finally shown to the user.
+
+### **Case 2: Abnormal event analysis**
+
+The traffic administration department can use the IVS system to find an abnormal event in the work area. For example, the vehicle violation detection function component is deployed in the edge
+
+computing servers for the IVS system, which then automatically detects the illegal parking event and notifies the traffic administrator.
+
+Step 1: The user logs into the IVS system through the CU, chooses some PUs which are deployed at the interested regions and configures the illegal parking detection function. They then submit the request to the IVS system.
+
+Step 2: After receiving the request, the IVS system authenticates the user information, and configures the illegal parking detection function of the corresponding edge computing servers. The IVS system then responds to the CU with the information of the illegal parking detection function.
+
+Step 3: The edge servers pull the video streams from the corresponding PUs, perform the illegal parking detection function online, and then sends the analysis results to the IVS system which are finally shown to the user.
+
+### **Case 3: Surveillance video preprocessing**
+
+The edge computing servers in the IVS system can support online video preprocessing such as pixel brightness transformation, geometric transformation, image smoothing, and edge detection. The output of the video preprocessing can be used for the accurate understanding of video content. However, the video preprocessing algorithms are quite different for the different video analysis functions. Thus, the administrator of the system can configure the video preprocessing functions in the edge computing servers according to further demand of video analysis.
+
+## **6.2 Collaborative computing based on intelligent premises units (IPUs) and edge computing servers**
+
+Currently, many intelligent premises units (IPUs) deployed on the roadside have vehicle structuring functions, e.g., vehicle detection, vehicle colour recognition, and vehicle type recognition. Meanwhile, the intelligent vehicle retrieval function component deployed in the edge computing servers can be configured according to the user's request.
+
+Step 1: The user logs into the IVS system through the CU. Sets several functional parameters such as the channel numbers of the related IPUs with the vehicle structuring function, and the picture of the target vehicle, and then sends the online vehicle retrieval request to the IVS system.
+
+Step 2: After receiving the request, the IVS system authenticates the user information, and analyses the key features of the target vehicle in the picture.
+
+Step 3: The IVS system configures the related IPUs and the online vehicle retrieval function in the related edge computing servers, and then sends the detected features of the target vehicle to the edge computing servers.
+
+Step 4: After loading the vehicle retrieval function, the edge IPUs detect the features of the vehicle in the surveillance video streams, and then the detected results are transmitted to the edge computing servers for real-time vehicle retrieval. If the features of the received data from the IPUs match the attributes of the target vehicle successfully, the retrieval results are sent back to the IVS system which notifies the user instantly.
+
+## **6.3 Collaborative edge-cloud computing**
+
+### **Case 1: Collaborative edge-cloud retrieval**
+
+Owing to the limited resources and data of the edge devices, the video processing results of the edge computing servers can be transmitted to the remote cloud computing platform for further analysis. For example, Tom is an administrator of an IVS system. In the case of vehicle retrieval, when Tom logs into the IVS system through the CU, he can set the channel numbers of the PUs for vehicle retrieval. The edge computing servers can detect the vehicles in the monitoring video streams after loading the vehicle detection function, and then the detected vehicle pictures are transmitted to the
+
+remote cloud platform for real-time vehicle retrieval. The remote cloud platform can compare the vehicle pictures from the edge computing platform with samples in the vehicle database and send back the retrieval results to the IVS system.
+
+### **Case 2: Collaborative edge-cloud alarm linkage**
+
+The VS system allows users to configure the collaborative edge-cloud alarm linkage. When the edge computing server reports an alarm event, the remote cloud computing platform performs the associated actions, such as recording, sending messages, and sending emails.
+
+#### **Case 3: Collaborative edge-cloud data subscription**
+
+The remote cloud computing platform can subscribe to the intelligent video metadata and the service alarm data generated by the edge computing platform. If the subscribed data is generated on the edge computing platform, it will be sent to the cloud computing platform directly.
+
+## **6.4 Regional PU/IPU management based on edge computing servers**
+
+The edge computing servers are usually deployed at the video surveillance (VS) network edge close to the PU/IPU. Once the VS system has been deployed, the edge computing servers can automatically discover the regional PUs/IPUs within the local network, and then connect with the central management platform of the VS system. For example, Tom is an administrator of a VS system. When Tom logs into the VS system through the CU, he can set the region name of each edge computing server and the channel name of each PU/IPU within the management region of the edge server. The edge computing server can provide the related interfaces for the management of the regional PUs/IPUs, such as addition, deletion, modification, searching browsing, pan/tilt/zoom (PTZ) control, local data storage and management, media distribution for the regional PUs/IPUs.
+
+## **6.5 Video storage**
+
+The edge computing server can access its regional PUs/IPUs, and the video data captured by the PUs/IPUs can be stored in the local edge computing server instead of being stored in the remote central management platform or the cloud storage system. When Tom logs into the VS system through the CU, he can replay the history video files stored in the edge computing server according to the channel name of the PU/IPU and the video start time. The edge computing server can provide the related interfaces for the playback of the history video files, such as fast-forward, fast-backward, pause, stop, and volume adjustment.
+
+## **6.6 Resource, task, and algorithm management**
+
+The edge computing platform can manage the video processing algorithms stored in it. A video processing task is a running instance of a video processing algorithm. The resources of the edge computing server, including computing and storage resources, etc., can be allocated to the video tasks deployed on it flexibly, and the video tasks can be deployed on the edge computing server dynamically. The edge computing platform can manage the resources of distributed edge servers remotely and configure the video processing tasks on demand, which can reduce operation and maintenance costs.
+
+# **7 Requirements for edge computing in video surveillance**
+
+## **7.1 User requirements**
+
+- USR-001: An edge computing platform supporting video surveillance (ECPVS) is required to support the registration and de-registration of the end user, and the end user can view and modify the personal information.
+
+- USR-002: An ECPVS is required to support the end user login and logout from the platform conveniently. The username and password are required when an end user logs into the platform.
+- USR-003: An ECPVS is recommended to support the end user view of the user access logs or other platform logs.
+- USR-004: An ECPVS is required to support the end user view of the information of the edge computing server, including name, status, capabilities, location, and other information of the edge computing server.
+- USR-005: An ECPVS is required to support the end user use the different platform services, including video storage and playback, video distribution, video processing, resource management, task management, and algorithm management through the graphical user interface or application programming interfaces.
+
+## 7.2 Service requirements
+
+### 7.2.1 Video analysis service requirements
+
+- SER-001: An ECPVS is recommended to support the video analysis. The video analysis components deployed in the edge computing server can receive the video streams from PUs/IPUs and perform the analysis functions online and process the video files stored in the local edge computing server offline.
+- SER-002: An ECPVS is recommended to support the management of the video processing algorithm repository, including algorithm addition, algorithm modification, and algorithm deletion. The video processing algorithm repository is a subsystem in the ECPVS, which is used for the algorithm storage and can be accessed by the corresponding management interfaces.
+- SER-003: An ECPVS is recommended to support the management of the video processing tasks in the edge computing servers, such as creation, pause, restart, and deletion. And an ECPVS is recommended to support the concurrent running of multiple video processing tasks.
+- SER-004: An ECPVS is recommended to support the view of the progress of the video analysis tasks.
+- SER-005: An ECPVS is recommended to support the view of the status of the resource utilized by the video analysis tasks.
+- SER-006: An ECPVS is recommended to support the view of the log files which record the operations of the video analysis tasks.
+
+### 7.2.2 Collaborative computing service requirements
+
+- SER-007: An ECPVS is recommended to support the collaborative end-edge computing based on the IPUs and edge computing servers. The intelligent video collaborative computing components deployed in the edge computing server can further analyse the results processed by the IPUs collaboratively.
+- SER-008: An ECPVS is recommended to support the collaborative edge-cloud computing mode. The video processing results output by the intelligent analysis components deployed in edge servers can be further analysed by the intelligent cloud computing platform collaboratively.
+- SER-009: An ECPVS is recommended to support the alarm linkage between the edge computing platform and the remote cloud computing platform. Consequently, the remote cloud computing platform can perform the associated actions, such as recording, sending messages, or emails when an alarm event is generated by the edge computing platform.
+
+- SER-010: An ECPVS is recommended to support the subscription of the intelligent video metadata and the service alarm data from the other computing platform.
+- SER-011: An ECPVS is recommended to support the management of the intelligent video collaborative computing tasks, such as creation, pause, restart, and deletion.
+- SER-012: An ECPVS is recommended to support the view of the progress of the intelligent video collaborative computing tasks.
+- SER-013: An ECPVS is recommended to support the view of the status of the resource utilized by the collaborative computing tasks.
+- SER-014: An ECPVS is recommended to support the view of the log files which record the operations of the collaborative computing tasks.
+
+### **7.2.3 Regional PU/IPU management service requirements**
+
+- SER-015: An ECPVS is recommended to support the management of the regional PUs/IPUs, such as addition, deletion, modification, searching, browsing, PTZ control of regional PUs/IPUs, and media distribution for regional PUs/IPUs.
+- SER-016: An ECPVS is recommended to support the view of the log files which record the operations of the regional PU/IPU management service.
+
+### **7.2.4 Video storage service requirements**
+
+- SER-017: An ECPVS is recommended to support the storage of the surveillance video captured by the regional PUs/IPUs.
+- SER-018: An ECPVS is recommended to support the video data management capabilities, including browsing, searching, playback, download, and deletion of the locally stored video files.
+- SER-019: An ECPVS is recommended to support the configuration for the local video storage, including setting the time for recording video, setting the time for video retention, etc.
+
+## **7.3 Security requirements**
+
+### **7.3.1 Authentication security requirements**
+
+- SEC-001: An ECPVS is required to provide the mechanisms for authentication and authorization, and it is required to only permit the authorized users to access the platform and use the platform services. An ECPVS is required to forbid an unauthorized user to handle any resources of the platform.
+- SEC-002: An ECPVS is required to support the multi-level user rights management and implement the fine-grained user group authority control.
+
+### **7.3.2 Access security requirements**
+
+- SEC-003: An ECPVS is required to operate in the environment where network address translation (NAT) and/or firewall devices are present. It is recommended to utilize the specified firewalls, gatekeepers, and other network devices to ensure the security for access to some special edge computing services.
+
+### **7.3.3 Content security requirements**
+
+- SEC-004: An ECPVS is required to ensure the security of the stored video files, the results of the video processing, etc.
+- SEC-005: An ECPVS is required to protect user privacy.
+- SEC-006: An ECPVS is recommended to support the addition of the digital watermark in the video of the specified cameras.
+
+- SEC-007: An ECPVS is recommended to support the media transmission encryption including video streaming encryption and image encryption during media transmission.
+
+### **7.3.4 System security requirements**
+
+- SEC-008: An ECPVS is required to have the capability of resisting various attacks.
+- SEC-009: An ECPVS is required to provide the mechanisms for troubleshooting. It is required that a structural single-node problem be avoided (i.e., a problem at a single node should not cause the failure of the entire platform).
+
+## **7.4 Management requirements**
+
+### **7.4.1 Resource management requirements**
+
+- MAN-001: An ECPVS is required to provide the unified management of the edge computing servers.
+- MAN-002: An ECPVS is recommended to support the resource management of the edge computing servers, such as computing resources, and storage resources. The resources can be allocated and withdrawn flexibly according to the service requests.
+- MAN-003: An ECPVS is recommended to monitor, record, search, and display the operational status of the resources.
+
+### **7.4.2 Tasks management requirements**
+
+- MAN-004: An ECPVS is recommended to support the dynamic task deployment in the edge computing servers, and the edge computing tasks can be installed and uninstalled flexibly according to the service requests.
+- MAN-005: An ECPVS is recommended to support the computing task management, including configuration, addition, deletion, migration, search, and browsing of the edge computing tasks.
+- MAN-006: An ECPVS is recommended to monitor, record, search, and display the status of the edge computing tasks.
+
+### **7.4.3 Algorithm management requirements**
+
+- MAN-007: An ECPVS is recommended to support the algorithm management, including addition, deletion, update, search, and browsing of the edge computing algorithms in the video algorithm repository. The video processing algorithms are usually stored in the video algorithm repository subsystem which can be accessed by the corresponding interfaces.
+
+### **7.4.4 Service management requirements**
+
+- MAN-008: An ECPVS is recommended to provide the capabilities of selecting the specific invoking location of various services among the edge computing servers.
+- MAN-009: An ECPVS is recommended to provide the various computing service subscription means for users and the capabilities of querying, viewing, and modifying their subscription information of the edge computing services.
+- MAN-010: An ECPVS is recommended to provide the capability of accounting, billing, and charging for the edge computing service operation.
+- MAN-011: An ECPVS is recommended to provide the various alternative accounting modes, and to support flexible combination of payment modes, billing modes, billing cycles, preferential pricing, etc.
+
+### **7.4.5 System management requirements**
+
+- MAN-012: An ECPVS is required to provide the unified system management interface which can be called conveniently.
+
+- MAN-013: An ECPVS is recommended to provide the graphical user interface.
+
+## **7.5 Scalability requirements**
+
+- SCA-001: An ECPVS is required to provide resource scalability. When the edge computing servers are increased or decreased, the edge computing capability of the ECPVS is increased or decreased accordingly, and the platform services are uninterrupted.
+- SCA-002: An ECPVS is recommended to provide the resource scalability for each specific edge computing task. The computing and storage resources of individual edge computing tasks can be increased or decreased according to the user's demand.
+
+## **7.6 Reliability requirements**
+
+- REL-001: An ECPVS is required to ensure the reliability of the edge computing services. When some edge computing servers have failed, the other edge computing servers should be guaranteed to operate normally, and the corresponding edge computing services can be used normally.
+- REL-002: An ECPVS is recommended to support the continuous video data transmission after network interruption to ensure that the video is not be lost.
+- REL-003: An ECPVS is required to support the autonomy ability of the edge computing server to continue its service when the edge computing server is disconnected from the central management platform due to unreliable network condition. While the network condition improves, the connection between the central management platform and the edge computing server will be established and the data of both sides will be synchronized again.
+
+## **7.7 Performance requirements**
+
+- PER-001: An ECPVS is required to support the concurrent user operations. The system can serve many users simultaneously while ensuring the quality of service.
+- PER-002: An ECPVS is required to support the concurrent execution of the different tasks while ensuring task execution efficiency.
+
+## Bibliography
+
+- [b-ITU-T H.626V2] Recommendation ITU-T H.626 (2019), *Architectural requirements for a video surveillance system.*
+- [b-ITU-T Y.101] Recommendation ITU-T Y.101 (2000), *Global Information Infrastructure terminology: Terms and definitions.*
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.743.13-202203-I_PDF-E/raw.md

@@ -0,0 +1,448 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.13**
+
+(03/2022)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for the cooperation of multiple  
+edge gateways**
+
+Recommendation ITU-T F.743.13
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters "ITU" in a bold, sans-serif font superimposed on the globe.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## Recommendation ITU-T F.743.13
+
+## Requirements for the cooperation of multiple edge gateways
+
+## Summary
+
+Recommendation ITU-T F.743.13 describes the requirements for a function that enables the cooperation of multiple edge gateways (CMEG) to complete complex tasks. It also describes the required capabilities and requirements of key components. The CEMG function can support the information exchanging among multiple edge gateways and deal with gateway failure cooperatively. It can also specify the central gateway which is responsible for selecting a cooperative gateway for each gateway, which in turn monitors the status of its partner gateway and manages the cooperative data and devices.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.13 | 2022-03-16 | 16          | <a href="http://handle.itu.int/11.1002/1000/14954">11.1002/1000/14954</a> |
+
+## Keywords
+
+Cooperation, gateway failure, multiple edge gateways.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2022
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                     | Page |
+|-----------------------------------------------------|------|
+| 1 Scope .....                                       | 1    |
+| 2 References.....                                   | 1    |
+| 3 Definitions .....                                 | 1    |
+| 3.1 Terms defined elsewhere .....                   | 1    |
+| 3.2 Terms defined in this Recommendation.....       | 2    |
+| 4 Abbreviations and acronyms .....                  | 2    |
+| 5 Conventions .....                                 | 2    |
+| 6 Overview .....                                    | 2    |
+| 7 Key components of the CMEG function .....         | 3    |
+| 8 Requirements for CMEG.....                        | 4    |
+| 8.1 General requirements.....                       | 4    |
+| 8.2 Requirements for the central role function..... | 5    |
+| 8.3 Requirements for the selection function.....    | 5    |
+| 8.4 Requirements for the control function.....      | 5    |
+| 8.5 Requirements for the monitoring function .....  | 5    |
+| 8.6 Requirements for management function .....      | 6    |
+| 9 Security considerations.....                      | 6    |
+| Appendix I – Scenarios.....                         | 7    |
+| Bibliography.....                                   | 8    |
+
+
+
+## Recommendation ITU-T F.743.13
+
+## Requirements for the cooperation of multiple edge gateways
+
+## 1 Scope
+
+This Recommendation describes requirements for a function that enables the cooperation of multiple edge gateways. This Recommendation covers the following:
+
+- key components and functionalities;
+- requirements of the cooperation of multiple edge gateways.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T Y.2201] Recommendation ITU-T Y.2201 (2009), *Requirements and capabilities for ITU-T NGN*.
+
+[ITU-T Y.2701] Recommendation ITU-T Y.2701 (2007), *Security requirements for NGN release 1*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 augmented reality** [b-ITU-T J.301]: A type of mixed reality where graphical elements are integrated into the real world in order to enhance user experience and enrich information.
+
+**3.1.2 Internet of Things** [b-ITU-T Y.2060]: A global infrastructure for the information society, enabling advanced services by interconnecting (physical and virtual) things based on existing and evolving interoperable information and communication technologies.
+
+NOTE 1 – Through the exploitation of identification, data capture, processing and communication capabilities, the IoT makes full use of things to offer services to all kinds of applications, whilst ensuring that security and privacy requirements are fulfilled.
+
+NOTE 2 – From a broader perspective, the IoT can be perceived as a vision with technological and societal implications.
+
+**3.1.3 network functions virtualization** [b-ITU-T L.1361]: Principle of separating network functions from the hardware they run on by using virtual hardware abstraction.
+
+**3.1.4 quality of service** [b-ITU-R BT.1833]: The collective effect of service performance which determines the degree of satisfaction of a user of the service.
+
+**3.1.5 virtual machine** [b-ITU-T Q.1743]: A software program that simulates a hypothetical computer central processing unit. The programs executed by a virtual machine are represented as byte codes, which are primitive operations for this hypothetical computer.
+
+### 3.2 Terms defined in this Recommendation
+
+None
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                       |
+|------|---------------------------------------|
+| AR   | Augmented Reality                     |
+| CMEG | Cooperation of Multiple Edge Gateways |
+| IoT  | Internet of Things                    |
+| NFV  | Network Functions Virtualization      |
+| QoS  | Quality of Service                    |
+| VM   | Virtual Machine                       |
+
+## 5 Conventions
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement that must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+- The keywords "is recommended" indicate a requirement that is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+## 6 Overview
+
+With the technological development of user devices, such as smartphones, laptops, Internet of Things (IoT) devices, wearable devices and connected vehicles, many computationally intensive applications are emerging, such as face recognition, augmented reality (AR) services and self-driving [b-Pavel]. Due to limited computation and battery resources of user devices, cloud computing has been developed to provide computing power and storage to help user devices with their computationally sensitive applications. However, the long propagation latency between user devices to the cloud, limits the quality of service (QoS) for some latency-sensitive applications, for example, autonomous driving [b-Yuyi].
+
+To reduce the response time and handle the rapidly increasing amount of data, it is a trend to offload some or all of the computing tasks to the edge network. Leveraging the computation resources and storage of gateways close to the user devices can provide high performance for computation-intensive and latency-sensitive applications. Using recent advancements in network functions virtualization (NFV), edge gateways can perform a service by creating a virtual machine (VM) for that service.
+
+As shown in Figure 6-1, the cloud has vast computing resources but it is far away from the users, while edge gateways are much closer to the users and have a certain amount of computing resources. When there are large numbers of edge gateways in some scenarios, they can cooperate with each other to provide more computing resources to the users and help each other.
+
+![Figure 6-1: An illustration of providing services using cloud and edge gateways. The diagram shows three layers: Cloud (Data platform), Edge gateway (Wireless, Wired, Wireless), and User equipment (Smartphone, Laptop, Connected vehicles, Health care, Smart home). Vertical arrows indicate 'Distance to user' from 'Far' to 'Near'.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+```
+
+graph TD
+    subgraph Cloud
+    DP[Data platform]
+    end
+    
+    I((Internet))
+    
+    subgraph Edge_Gateway_Layer [Edge gateway]
+    WEG1[Wireless edge gateway]
+    WiredEG[Wired edge gateway]
+    WEG2[Wireless edge gateway]
+    end
+    
+    subgraph User_Equipment_Layer [User equipment]
+    SP[Smartphone]
+    L[Laptop]
+    CV[Connected vehicles]
+    HC[Health care]
+    SH[Smart home]
+    end
+
+    DP <--> I
+    I <--> WiredEG
+    WEG1 --- User_Equipment_Layer
+    WiredEG --- User_Equipment_Layer
+    WEG2 --- User_Equipment_Layer
+
+```
+
+The diagram illustrates a three-tier architecture for service provision. At the top, the 'Cloud' layer contains a 'Data platform' connected to the 'Internet'. The middle 'Edge gateway' layer consists of three units: a 'Wireless edge gateway', a 'Wired edge gateway', and another 'Wireless edge gateway'. The bottom 'User equipment' layer includes icons for a 'Smartphone', 'Laptop', 'Connected vehicles' (car, bus), 'Health care' (doctor, medical bag), and a 'Smart home' (house with gear). Vertical double-headed arrows connect the Data platform to the Internet, the Internet to the edge gateways, and the edge gateways to the user equipment. On the left, dashed vertical arrows label the layers: 'Cloud', 'Edge gateway', and 'User equipment'. On the right, a solid vertical arrow labeled 'Distance to user' points from 'Far' at the top to 'Near' at the bottom. The reference 'F.743.13(22)' is noted at the bottom right.
+
+Figure 6-1: An illustration of providing services using cloud and edge gateways. The diagram shows three layers: Cloud (Data platform), Edge gateway (Wireless, Wired, Wireless), and User equipment (Smartphone, Laptop, Connected vehicles, Health care, Smart home). Vertical arrows indicate 'Distance to user' from 'Far' to 'Near'.
+
+**Figure 6-1 – An illustration of providing services using cloud and edge gateways**
+
+Four service scenarios are given in the appendix for informational purposes.
+
+## 7 Key components of the CMEG function
+
+This clause addresses the capabilities of the key components of the CMEG function.
+
+![Figure 7-1: Illustration of the CMEG function. It shows a network of gateways (A-G) with central roles (A and B) and cooperation relations. A legend defines 'Cooperation relation' as a dashed arrow and 'Connection relation' as a solid arrow.](367926125450c2bc3f4bdca9d59a62ba_img.jpg)
+
+```
+
+graph TD
+    A[Gateway A  
+assuming the central role  
+of the CMEG function  
+(Coop. of C)]
+    B[Gateway B  
+assuming the CMEG standby  
+central role  
+(Coop. of A)]
+    C[C  
+(Coop. of E and F)]
+    D[D]
+    E[E  
+(Coop. of D)]
+    F[F  
+(Coop. of B and G)]
+    G[G]
+
+    A --- B
+    A --- C
+    B --- F
+    C --- E
+    C --- F
+    E --- D
+    F --- G
+
+    A -.-> B
+    C -.-> A
+    E -.-> C
+    D -.-> E
+    F -.-> B
+    G -.-> F
+
+```
+
+This diagram shows the CMEG function across a network of gateways. Gateway A is the central role, and Gateway B is the standby central role. Gateways are represented by icons of a router and a server. Solid lines represent 'Connection relations', and dashed lines represent 'Cooperation relations'. Gateway A (Coop. of C) is connected to Gateway B (Coop. of A) and Gateway C (Coop. of E and F). Gateway B is connected to Gateway F (Coop. of B and G). Gateway C is connected to Gateway E (Coop. of D), which is connected to Gateway D. Gateway F is connected to Gateway G. The reference 'F.743.13(22)' is noted at the bottom right. A legend at the bottom left defines the arrow types: 'Cooperation relation' (dashed) and 'Connection relation' (solid).
+
+Figure 7-1: Illustration of the CMEG function. It shows a network of gateways (A-G) with central roles (A and B) and cooperation relations. A legend defines 'Cooperation relation' as a dashed arrow and 'Connection relation' as a solid arrow.
+
+**Figure 7-1 – Illustration of the CMEG function**
+
+Figure 7-1 shows an illustration of several edge gateways with CMEG function and each gateway connects to different user devices.
+
+In this system, one edge gateway will take on the central role of the CMEG function and another gateway will take on the CMEG standby central role. These two gateways are selected based on their status, such as storage capacity, processing speed, average bandwidth, operating stability, and other parameters. The gateway assuming the central role will assign a cooperative gateway to each edge gateway based on the collected status of each edge gateway, such as location, energy situation, communication capability, etc. The cooperative gateway of an edge gateway is responsible for monitoring its status and backing up its data. For example, in Figure 7-1, E is the cooperative gateway for D and C is the cooperative gateway for E and F.
+
+![Diagram showing the key components of the CMEG function. A large rounded rectangle contains five stacked boxes labeled from top to bottom: Central-Role function, Selection function, Control function, Monitoring function, and Management function. Below these boxes, the text 'CMEG function' is centered within the large rectangle.](cfda9df1319e04207eb28bcefd1dab7b_img.jpg)
+
+The diagram illustrates the key components of the CMEG function. It consists of a large rounded rectangle containing five stacked boxes, each representing a functional unit. From top to bottom, these are: Central-Role function, Selection function, Control function, Monitoring function, and Management function. Below the boxes, the text 'CMEG function' is centered within the large rectangle.
+
+Diagram showing the key components of the CMEG function. A large rounded rectangle contains five stacked boxes labeled from top to bottom: Central-Role function, Selection function, Control function, Monitoring function, and Management function. Below these boxes, the text 'CMEG function' is centered within the large rectangle.
+
+F.743.13(22)
+
+**Figure 7-2 – Key components of the CMEG function**
+
+As shown in Figure 7-2, the core of the CMEG function is the gateway cooperation. To handle gateway cooperation, CMEG has four key functional units, namely, central role, selection, control, monitoring and management unit.
+
+The central-role function is responsible for gathering various information about the edge gateways and assigning a cooperative gateway for each gateway.
+
+The selection function is responsible for calculating its quality score, which represents its suitability for taking on the central role, based on the state of the gateway such as the parameters of its storage capacity, processing speed, average bandwidth and operating stability, and selecting appropriate gateways for the CMEG function, including identifying one gateway to assume the central role and another one for backup and assigning a cooperative gateway to each gateway.
+
+The control function is responsible for controlling the cooperative relationship between gateways, including establishing/releasing the cooperative relationship.
+
+The monitoring function is responsible for monitoring the activity status of the cooperative gateway.
+
+The management function is responsible for managing the cooperative data and user devices of the cooperative gateway if necessary.
+
+## **8 Requirements for CMEG**
+
+This clause addresses the requirements for CMEG.
+
+### **8.1 General requirements**
+
+GEN-01: The CMEG function is required to support the exchange of information between multiple edge gateways, including control information and data.
+
+GEN-02: The CMEG function is recommended to enable multiple edge gateways to cooperate on computational tasks.
+
+GEN-03: The CMEG function is required to enable multiple edge gateways to cooperate in case of gateway failures.
+
+GEN-04: The CMEG function is recommended to support the cooperative management of computing, storage, and communication resources across edge gateways.
+
+### **8.2 Requirements for the central role function**
+
+CR-01: The central role function is required to gather various information about the edge gateways, including the connectivity relationships between them.
+
+CR-02: The central role function is required to assign a cooperative gateway to each gateway. The selected cooperating gateway should meet the predefined requirements, e.g., distance requirements.
+
+CR-03: The central role function is required to assign a new cooperative gateway for one gateway, if the previously assigned cooperative gateway fails for an extended period of time.
+
+CR-04: The central role function is required to assign a new cooperative gateway to a gateway if the previously assigned cooperative gateway feeds back that it does not have enough resources to support cooperation.
+
+### **8.3 Requirements for the selection function**
+
+SU-01: The selection function of each gateway is required to calculate its quality score.
+
+SU-02: The selection function of each gateway is required to exchange its Q value with the neighbouring gateways.
+
+SU-03: The selection function of each gateway is required to select one gateway that will assume the central role based on the Q values collected from all the neighbouring gateways, using a common policy and algorithm.
+
+SU-04: The selection function of each gateway can optionally send Q values to a third party (e.g., a cloud platform), which will determine the gateways that will take on the central and standby roles.
+
+### **8.4 Requirements for the control function**
+
+CU-01: The control function of each gateway is required to receive assignment instructions from a central role for its cooperative gateway.
+
+CU-02: The control function of each gateway is required to establish a connection with its cooperative gateway assigned by the central role and inform the other party of its resource requirements.
+
+CU-03: After receiving the resource requirements from its cooperative gateway, the control function of this gateway is required to determine whether to establish a partnership or refuse to establish a partnership, depending on its own resources.
+
+CU-04: The control function of each gateway is required to request the central role to assign a new cooperative gateway if the previous one refuses to establish a partnership.
+
+### **8.5 Requirements for the monitoring function**
+
+MU-01: The monitoring function of each gateway is required to monitor the active status of its cooperative gateway, actively or passively.
+
+MU-02: The monitoring function of each gateway is required to inform the central role in time if its cooperative gateway is offline.
+
+MU-03: The monitoring function of the central role is required to determine whether a gateway is temporarily offline or permanently offline.
+
+### **8.6 Requirements for management function**
+
+MU-01: The management function of each gateway is required to back up the data of its cooperative gateway.
+
+MU-02: The management function of each gateway is required to delete the backup data stored locally of its cooperative gateway at the request of the latter.
+
+MU-03: In case its cooperating gateway is offline, the management function of this gateway is recommended to send backup data of its cooperative gateway to the data platform.
+
+MU-04: In case its cooperating gateway is offline for an extended period of time, the management function of this gateway is recommended to negotiate with the devices originally managed by the cooperative gateway and if possible, become the gateway to which they are connected.
+
+## **9 Security considerations**
+
+It is recommended that the security requirements of [ITU-T Y.2201], [ITU-T Y.2701], and applicable ITU-T X-series, ITU-T Y-series, and ITU-T M-series security Recommendations be taken into consideration, which includes access control, authentication, data confidentiality, communications security, data integrity, availability and privacy.
+
+## **Appendix I**
+
+## **Scenarios**
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Four typical service scenarios are described here, in which multiple edge gateways cooperate with each other supported by the CMEG function defined in this Recommendation.
+
+1. A service for one user is split into multiple sub-tasks which are accomplished by multiple edge gateways in collaboration, and the results of the sub-tasks are returned to the user.
+2. A service requires data collected from multiple locations. The data is collected and pre-processed by multiple edge gateways, and the results are then sent to the data platform. For example, an environmental monitoring service needs to collect data from multiple locations. Multiple IoT devices are connected to several gateways. These edge gateways cooperate with each other to collect data and pre-process these data as required.
+3. A service needs to collect data from one set of devices and needs to trigger another set of devices connected to another edge gateway. For example, a fire monitoring service collects data from smoke detectors. If the edge gateway determines that a fire has occurred, it needs to notify a fire door connected to another edge gateway, triggering a fire alarm and closing the door at the same time.
+4. Many edge gateways work in store-and-forward mode where they collect and store data in advance and report it to the platform when needed. The collected data might be lost due to the failure of the edge gateway. If one gateway has one backup gateway, referred to as a cooperative gateway in this Recommendation, to back up the collected data, when it fails, its cooperative gateway will discover the failure and upload the backup data on its behalf.
+
+## Bibliography
+
+- [b-ITU-T J.301] Recommendation ITU-T J.301 (2014), *Requirements for augmented reality smart television systems.*
+- [b-ITU-T L.1361] Recommendation ITU-T L.1361 (2018), *Measurement method for energy efficiency of network functions virtualization.*
+- [b-ITU-T Q.1743] Recommendation ITU-T Q.1743 (2016), *IMT-Advanced references to Release 11 of LTE-Advanced evolved packet core network.*
+- [b-ITU-T Y.2060] Recommendation ITU-T Y.4000/Y.2060 (2012), *Overview of the Internet of things.*
+- [b-ITU-R BT.1833] Recommendation ITU-T BT.1833 (2014), *Broadcasting of multimedia and data applications for mobile reception by handheld receivers.*
+- [b-Pavel] Pavel, M., and Zdenek, B. (2017), *Mobile edge computing: A survey on architecture and computation offloading.* IEEE Communications Surveys & Tutorials.  
+<<https://ieeexplore.ieee.org/document/7879258>>
+- [b-Yuyi] Yuyi, M., Changsheng, You., Jun, Zhang., Kaibin, Huang., and Khaled, B. L. (2017), *Mobile Edge Computing: Survey and Research Outlook.*  
+<[https://www.researchgate.net/publication/312061424\\_Mobile\\_Edge\\_Computing\\_Survey\\_and\\_Research\\_Outlook](https://www.researchgate.net/publication/312061424_Mobile_Edge_Computing_Survey_and_Research_Outlook)>
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.14**
+
+(03/2022)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for video distribution systems**
+
+Recommendation ITU-T F.743.14
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in white, bold, sans-serif font superimposed on the globe.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.743.14
+
+# Requirements for video distribution systems
+
+## Summary
+
+Recommendation ITU-T F.743.14 describes the requirements and application scenarios for video distribution systems. A video distribution system is an Internet application system that is built based on the underlying content delivery network, and can provide the video collection, distribution and viewing functions for Internet users without any system development.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.14 | 2022-03-16 | 16          | <a href="http://handle.itu.int/11.1002/1000/14955">11.1002/1000/14955</a> |
+
+## Keywords
+
+Live streaming, requirements, video distribution, video on demand.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2022
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                 | Page |
+|---------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                   | 1    |
+| 2 References.....                                                               | 1    |
+| 3 Definitions .....                                                             | 1    |
+| 3.1 Terms defined elsewhere .....                                               | 1    |
+| 3.2 Terms defined in this Recommendation.....                                   | 1    |
+| 4 Abbreviations and acronyms .....                                              | 1    |
+| 5 Conventions .....                                                             | 2    |
+| 6 Introduction .....                                                            | 2    |
+| 7 Requirements for video distribution system.....                               | 3    |
+| 7.1 User requirements.....                                                      | 3    |
+| 7.2 Service requirements .....                                                  | 4    |
+| 7.3 Security requirements .....                                                 | 5    |
+| 7.4 Quality of service (QoS) and quality of experience (QoE) requirements ..... | 6    |
+| 7.5 Accounting, charging and billing requirements .....                         | 6    |
+| 7.6 Other requirements .....                                                    | 6    |
+| Appendix I – Application scenarios for video distribution system.....           | 7    |
+| I.1 Online education.....                                                       | 7    |
+| I.2 Online corporate event .....                                                | 7    |
+| I.3 Live sports event.....                                                      | 8    |
+| I.4 Live e-commerce event .....                                                 | 8    |
+| Bibliography.....                                                               | 9    |
+
+
+
+# Recommendation ITU-T F.743.14
+
+## Requirements for video distribution systems
+
+# 1 Scope
+
+This Recommendation describes the requirements and application scenarios for video distribution systems.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T Y.2019] Recommendation ITU-T Y.2019 (2010), *Content delivery functional architecture in NGN*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 application** [b-ITU-T Y.101]: A structured set of capabilities, which provide value-added functionality supported by one or more services.
+
+**3.1.2 content delivery network** [b-ITU-T Y.2084]: A content delivery network (CDN) is a system of distributed servers that deliver content (e.g., web pages, files, videos and audios) to users based on pre-defined criteria such as the geographic locations of users, the status of the content delivery server and the IP network connection.
+
+**3.1.3 live streaming** [b-ITU-T Y.2084]: A video service in which a continuous stream flows in real-time from the service provider to the terminal device and the user cannot control the temporal order in which content is played.
+
+**3.1.4 service** [b-ITU-T Y.101]: A structured set of capabilities intended to support applications.
+
+**3.1.5 video on demand** [b-ITU-T Y.1910]: A service in which the end user can, on demand, select and view video content and where the end user can control the temporal order in which the video content is viewed (e.g., the ability to start the viewing, pause, fast forward, rewind).
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 video distribution system (VDS)**: An Internet application system that is built based on the video delivery networking platform such as CDN, and which can provide video collection, distribution and viewing functions for Internet users without any system development.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                           |
+|-----|---------------------------|
+| CDN | Content Delivery Network  |
+| QoE | Quality of Experience     |
+| QoS | Quality of Service        |
+| VDS | Video Distribution System |
+| VOD | Video On Demand           |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement that must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement that is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+# 6 Introduction
+
+For distributing video on the Internet, users can use the content delivery network (CDN defined in [ITU-T Y.2019]) or other improved video delivery networking platforms. Though it can avoid the technically complex implementation and operation of video delivery services from the video source to the destination, users need to also develop their own network video applications with the service capabilities provided by the video delivery networking platform. Therefore, it requires users to have the ability of system development. There is a time-consuming development process before users can access the video distribution application.
+
+VDS is an Internet application system that is built based on the video delivery networking platform such as CDN, and can provide the video collection, distribution and viewing functions for Internet users without any system development. Compared with the traditional video delivery platform such as CDN, VDS enables the users to carry out their video distribution business needs immediately and conveniently and avoid the complex application development and testing process. Figure 1 shows the reference model of VDS. As an Internet application system, to support a wider range of application scenarios, VDS needs to support the common functions and services including account management, live streaming, video on demand (VOD), video recording and storage, video playback, content audit, charging and billing, system operation and maintenance, etc. In addition, an external interactive messaging system is usually used to cooperate with the video distribution system to support instant messaging and comments for video content. The VDS administrator can create a video broadcasting channel or publish a VOD according to the application requirements and use the VDS to distribute the video on the Internet. The audience can then watch the video content produced by the administrator through the VDS.
+
+![Figure 1 – Reference model for video distribution systems. The diagram shows a central 'Video distribution system' (VDS) connected to an 'Interactive message system' at the top and a 'CDN' at the bottom. The VDS is divided into two main functional blocks: 'Account management, Charging and billing, Content audit, Video recording and storage' and 'Video service management unit' (containing 'Live stream management', 'Video on demand management', and 'System operation and maintenance'). The VDS is accessed by a 'VDS administrator' (left) and a 'VDS audience' (right). The administrator manages 'Online education', 'Live sport events', 'Online corporate events', and 'Live E-commerce events'. The audience also views these same categories. The CDN consists of a 'CDN centre node' connected to two 'CDN regional nodes', which are further connected to four 'CDN edge nodes'.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+Figure 1 – Reference model for video distribution systems. The diagram shows a central 'Video distribution system' (VDS) connected to an 'Interactive message system' at the top and a 'CDN' at the bottom. The VDS is divided into two main functional blocks: 'Account management, Charging and billing, Content audit, Video recording and storage' and 'Video service management unit' (containing 'Live stream management', 'Video on demand management', and 'System operation and maintenance'). The VDS is accessed by a 'VDS administrator' (left) and a 'VDS audience' (right). The administrator manages 'Online education', 'Live sport events', 'Online corporate events', and 'Live E-commerce events'. The audience also views these same categories. The CDN consists of a 'CDN centre node' connected to two 'CDN regional nodes', which are further connected to four 'CDN edge nodes'.
+
+F.743.14(22)
+
+**Figure 1 – Reference model for video distribution systems**
+
+# 7 Requirements for video distribution system
+
+## 7.1 User requirements
+
+Users can be divided into different roles, administrator, sub-administrator, and audience. Users of different roles participate in different parts of the system, so they have different requirements. The administrator can manage live video channels, VOD and sub-administrators. The sub-administrator can also manage live video channels and VOD, but they must have the corresponding authorities assigned by the administrator and the audience can watch videos through the system.
+
+### 7.1.1 Administrator requirements
+
+- USR-1: A VDS is required to support the registration and de-registration of the administrator through the interface provided by the system.
+- USR-2: A VDS is required to support the administrator to login and logout from the system conveniently. The username and password are required when the administrator logs into the system.
+- USR-3: A VDS is required to support the administrator to view and modify personal information, including name, password, identity information, etc.
+- USR-4: A VDS is required to support the administrator to manage the live video channels, including addition, deletion, modification, browsing, retrieval, audit and ban. The information of a live channel usually includes the name, introduction, watching conditions, start and end time, etc.
+- USR-5: A VDS is required to support the administrator to broadcast the live video through a created live video channel by using the video capturing and transmission devices.
+- USR-6: A VDS is recommended to support the administrator to get the real-time monitoring information of the live channels through the interface provided by the system, including the number of online audiences, the total number of viewings, etc.
+
+- USR-7: A VDS is required to support the administrator to manage the VOD, including addition, deletion, modification, browsing, retrieval, audit and ban. The information of a VOD usually includes the name, introduction, watching conditions, etc.
+- USR-8: A VDS is recommended to support the administrator to get the statistical viewing information of the VOD through the interface provided by the system, including the total number of viewings, etc.
+- USR-9: A VDS is required to support the administrator to manage the accounts of the sub-administrators, including addition, deletion, modification, browsing, retrieval and access control.
+- USR-10: A VDS is recommended to support the administrator to audit the interactive instant messages for the live video channel and the comments for the VOD.
+
+### **7.1.2 Sub-administrator requirements**
+
+- USR-11: A VDS is required to support the sub-administrator to login and logout from the system conveniently. The username and password are required when a sub-admin-user logs into the system.
+- USR-12: A VDS is required to support the sub-administrator to view and modify the personal information, including name, password, identity information, etc.
+- USR-13: A VDS is required to support the sub-administrator to manage the live video channels, broadcast the live video, and manage the VOD when the sub-administrator has the corresponding authorities assigned by the administrator.
+
+### **7.1.3 Audience requirements**
+
+- USR-14: A VDS is required to support the registration and de-registration of the audience through the interface provided by the system.
+- USR-15: A VDS is required to support the audience to login and logout from the system conveniently. The username and password are required when an audience logs into the system.
+- USR-16: A VDS is required to support the audience to watch the live broadcast video and the VOD.
+- USR-17: A VDS is recommended to support the bit rate conversion processing for the live video stream and the VOD to meet the reasonable heterogeneous viewing needs of different audiences in the different network environments.
+- USR-18: A VDS is recommended to support the interactive instant message function for the live broadcast channel and the comment function for the VOD.
+- USR-19: A VDS is recommended to support the report function from the audience when the live broadcast channel or the VOD contains the undesirable information.
+- USR-20: A VDS is recommended to support the content recommendation function of live video channels and the VOD for the audience according to their location and preference information.
+
+## **7.2 Service requirements**
+
+- SRV-1: A VDS is required to support the registration and de-registration of the user through the interface provided by the system.
+- SRV-2: A VDS is required to support the live video distribution from the video capturing devices to the audience viewing devices.
+- SRV-3: A VDS is required to support the VOD.
+- SRV-4: A VDS is required to support the storage and management of the video files.
+
+- SRV-5: A VDS is recommended to support the information collection and display of the live video channels and VOD, such as the number of online audiences, the total number of views, etc.
+- SRV-6: A VDS is recommended to support the transcoding of the live video stream, and the corresponding transcoding templates and configuration are provided.
+- SRV-7: A VDS is recommended to support the transcoding of the video files uploaded for the VOD, and the corresponding transcoding templates and configuration are provided.
+- SRV-8: A VDS is recommended to support the storage and playback of the live video stream.
+- SRV-9: A VDS is recommended to support the instant message interaction for the live broadcast channel and the comment for the VOD.
+- SRV-10: A VDS is recommended to support the audit and report the content of the live video channels and VOD.
+- SRV-11: A VDS is recommended to support the audit and report the instant message for the live broadcast channel and the comment for the VOD.
+- SRV-12: A VDS is recommended to support the content recommendation for the live video channels and the VOD.
+
+## **7.3 Security requirements**
+
+### **7.3.1 Access security requirements**
+
+- SEC-1: A VDS is required to provide the mechanisms for authentication and authorization. It is required to provide different interfaces for the users of different roles. Only the authorized user is allowed to access the corresponding part of the system and use the related function.
+- SEC-2: A VDS is required to provide the mechanisms for viewing condition certification. The audience should be checked whether they can watch the video according to the viewing conditions set by the system administrator.
+- SEC-3: A VDS is required to forbid an unauthorized user to push the live video stream to the system or publish the VOD through the system.
+
+### **7.3.2 Content security requirements**
+
+- SEC-4: A VDS is recommended to provide the security mechanisms for the video stream and stored video, such as video encryption, to ensure the integrity and secrecy of the video data.
+- SEC-5: A VDS is recommended to provide the mechanisms to protect the copyrights of the video streams and stored videos.
+- SEC-6: A VDS is recommended to provide the logo addition function for the live video stream and the VOD resources to maintain the copyright of the initiator of live broadcast and the uploader of the VOD resources.
+- SEC-7: A VDS is recommended to provide the detection and prevention function for the sensitive elements of the video content.
+
+### **7.3.3 System security requirements**
+
+- SEC-8: A VDS is required to protect user privacy. The password and other private information should be encrypted in the system.
+- SEC-9: A VDS is required to have a certain ability to resist vicious attacks.
+- SEC-10: A VDS is required to have the capability of disaster recovery. The system is recommended to use a hot backup to ensure the continuity of system running.
+- SEC-11: A VDS is recommended to provide the troubleshooting mechanism.
+
+## **7.4 Quality of service (QoS) and quality of experience (QoE) requirements**
+
+- QoS-1: A VDS is recommended to implement the QoS strategies on the application layer or on the transmission layer, or both. In cases of delay, jitter, sequence error and packet loss, the system is able to recover and repair the impairments and adjust the data stream in response to the changes in the network bandwidth.
+- QoS-2: A VDS is required to provide high-quality video transmission. When the live video or the recorded video is played, the images and the voice are required to be clear and fluent, and the multimedia is required to be synchronized.
+- QoS-3: A VDS is recommended to support the low end-to-end delay transmission of a live stream from the video capturing device to the audience viewing device, including time taken by encoding, network transmission, decoding and display.
+- QoS-4: A VDS is recommended to support the video frame rate with no lower than 25 frames/s (FPS).
+- QoS-5: A VDS is required to respond rapidly to the user's operation.
+- QoS-6: A VDS is required to provide enough storage space for recording and uploading video.
+
+## **7.5 Accounting, charging and billing requirements**
+
+- ACB-1: A VDS is recommended to provide the capability of accounting, charging, and billing for the system operation.
+- ACB-2: A VDS is recommended to support the view of the network traffic statistics and consumption bill details for the usage of the system services and provide the online payment channel for subscribing to the system services.
+
+## **7.6 Other requirements**
+
+- OTH-1: A VDS is required to support the scalability. When the resources of the system are increased, the system service capability is increased accordingly.
+- OTH-2: A VDS is required to support the concurrent user operations. The system can serve a large number of users simultaneously while ensuring the quality of service.
+- OTH-3: A VDS is recommended to minimize the resource costs for distribution and coding while maintaining the quality of service.
+
+## Appendix I
+
+### Application scenarios for video distribution system
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### I.1 Online education
+
+#### Case 1: Live online course
+
+The VDS can support the multi-person live course for teachers and students in different places through the Internet and enable online interaction effectively between them. Jack is an English teacher, and many of the students are not in the same city. Jack hopes to be able to teach online to bring together students from across the globe for the English course. Jack subscribes to the VDS service and plans to teach online through live broadcast. When Jack logs into the VDS, Jack can choose to create a live channel for the online English course. Jack needs to set name of the live channel, introduction, scale, start and end time and other basic information. To ensure that only the authenticated students can watch the live streaming course, Jack needs to set the viewing conditions of the live broadcast. When Jack starts the course live broadcast, the media capturing and transmission devices are required to produce the media stream of course content. Bob is one of Jack's students. Bob needs to enter the live channel and complete the authentication before watching the live broadcast. Also all the authenticated students can step into the online class at the same time anywhere and start learning. Moreover, the students can view the playback of the online course video recorded in the VDS.
+
+#### Case 2: Course on demand
+
+The VDS can provide the course playback based on the video on demand service for students to learn on their own, at their own pace, or on their own schedule. Jack records the English video course in advance and builds the VOD course in the following steps. Firstly, Jack logs into the VDS. Secondly, Jack chooses to create a new video-on-demand course and sets the name, introduction and other basic information of the course. In addition, Jack also needs to set the course viewing conditions to ensure that only the authenticated students can watch the video. Finally, Jack uploads the course video to the VD system and publishes it online. After the authentication of the VDS, Bob can watch the course on demand at any time. The VDS can also provide friendly interactive functions for the VOD courses at the viewing site, such as fast-forward, fast-backward, pause and stop.
+
+### I.2 Online corporate event
+
+#### Case 1: Product launch
+
+The VDS can support the online product launch for companies on the Internet. A company decides to launch a new product in the market. In order to better promote the product, the company plans to hold an online product launch to allow more people to watch the new product launch event at the same time. Concretely, the company can use the video distribution service provided by the VDS to create a live video channel for the product launch event. The administrator of the system needs to set the name, scale, introduction, start and end time, and other related information of the live broadcast channel. At the launch event site, several cameras can capture the live video from different perspectives, and a video switching and distribution device connected to the cameras can select a live video stream and push it to the created video channel of the VDS. Anyone from all over the world can watch the live broadcast of the online product launch through the VDS. Meanwhile, the VDS can forward the live streaming to the third-party video distribution platform to further increase the exposure of the product launch event.
+
+#### **Case 2: Employee training**
+
+The VDS can support online employee training for companies on the Internet when employees are in different places. Jack is an administrator of a large company with branches in different cities. Jack wants to give employees who are in different cities the latest skills training and hopes to be able to train online so that they can be trained offsite. Jack subscribes to the VDS service and logs into the VD system to create a live channel. Jack also needs to set the name of the live video channel, scale, introduction, start and end time and other basic information about the live channel. In addition, Jack needs to set the identity information of the employees who can watch this live training video in the system. Michael is the presenter of this training course. When Michael starts the live course broadcast, a set of video capturing and transmission device is required to transmit the live training stream to the video channel created in the VDS. Bob is an employee of the company. After passing the system authentication, Bob can watch the live training broadcast at the viewing site of the VDS. Meanwhile, Jack and/or Michael can view the instant audience information during the live broadcast, such as online users, comments about the training, etc.
+
+### **I.3 Live sports event**
+
+The VDS can support live video sharing for sports events. Smith is an organizer of a basketball game, and Smith wants to share the live game videos captured from different perspectives simultaneously on the Internet. Smith logs into the VDS, creates four live video channels for the game broadcast, and sets the name, introduction, start and end time, and other related information of the basketball game. When the game begins, four sets of video capturing and transmission devices around the playing field are used to push the multi-view game video streams to the corresponding video channels of the VDS simultaneously. Then, anyone who is interested in the basketball game can watch the live game video through the VDS. Moreover, Smith can choose the current best-view video channel from the four shared live video streams to watch the game.
+
+### **I.4 Live e-commerce event**
+
+The VDS can provide a live broadcast service for e-commerce participants to help them better promote their products online. Selina is a clothing e-commerce practitioner, and Selena's online store has many latest women's fashion clothing collections. Since the picture of the product gives very little information, Selina wants to use live video to introduce more details about the products and show how well put the clothes can be for the potential customers. Selena logs into the VDS, creates a live video channel, and sets the name, introduction, start and end time, product web link, and other basic information about the clothing e-commerce channel. A set of video capturing and transmission device is used to push the live video stream to the created channel of the VSS, and Selina can introduce and show the products to the visitors of the online shop through the system. Consequently, the visitors can learn more about the details of the products by watching the live e-commerce event, and conveniently buy the interesting products in Selina's online store linked by the video channel webpage.
+
+## Bibliography
+
+- [b-ITU-T Y.101] Recommendation ITU-T Y.101 (2000), *Global Information Infrastructure terminology: Terms and definitions.*
+- [b-ITU-T Y.1910] Recommendation ITU-T Y.1910 (2008), *IPTV functional architecture.*
+- [b-ITU-T Y.2084] Recommendation ITU-T Y.2084 (2015), *Distributed service networking content distribution functions.*
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.20**
+
+(08/2020)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Assessment framework for big data  
+infrastructure**
+
+Recommendation ITU-T F.743.20
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a stylized globe with a red lightning bolt striking across it. The letters 'ITU' are prominently displayed in blue and white.
+
+ITU logo
+
+International  
+Telecommunication  
+Union
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.743.20
+
+## Assessment framework for big data infrastructure
+
+## Summary
+
+Recommendation ITU-T F.743.20 provides an assessment framework of big data infrastructure, which includes functional metrics, performance metrics, scalability metrics, security metrics, operation metrics and compatibility metrics.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.20 | 2020-08-13 | 16          | <a href="http://handle.itu.int/11.1002/1000/14325">11.1002/1000/14325</a> |
+
+## Keywords
+
+Assessment framework, big data infrastructure.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2020
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|    |                                               |   |
+|----|-----------------------------------------------|---|
+| 1  | Scope .....                                   | 1 |
+| 2  | References.....                               | 1 |
+| 3  | Definitions .....                             | 1 |
+|    | 3.1 Terms defined elsewhere .....             | 1 |
+|    | 3.2 Terms defined in this Recommendation..... | 1 |
+| 4  | Abbreviations and acronyms .....              | 2 |
+| 5  | Conventions .....                             | 2 |
+| 6  | Overview .....                                | 2 |
+| 7  | Function metrics .....                        | 3 |
+| 8  | Performance metrics .....                     | 4 |
+| 9  | Scalability metrics .....                     | 4 |
+| 10 | Security metrics .....                        | 4 |
+| 11 | Operation metrics.....                        | 4 |
+| 12 | Compatibility metrics .....                   | 5 |
+
+
+
+# Recommendation ITU-T F.743.20
+
+## Assessment framework for big data infrastructure
+
+## 1 Scope
+
+This Recommendation defines the assessment framework for big data infrastructure system, which can be applied to design, development, testing, evaluation and acceptance of big data platforms. The scope of this Recommendation includes:
+
+- Function metrics in big data infrastructure,
+- Performance metrics in big data infrastructure,
+- Scalability metrics in big data infrastructure,
+- Security metrics in big data infrastructure,
+- Operation metrics in big data infrastructure,
+- Compatibility metrics in big data infrastructure.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T Q.3930] Recommendation ITU-T Q.3930 (2012), *Performance testing of distributed systems – Concepts and terminology*.
+
+[ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014) | ISO/IEC 17788: 2014, *Information technology – Cloud computing – Overview and vocabulary*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 cloud service user:** Natural person, or entity acting on their behalf, associated with a **cloud service customer** that uses **cloud services**.
+
+NOTE – Examples of such entities include devices and applications.
+
+**3.1.2 tenant** [ITU-T Y.3500]: One or more cloud service users sharing access to a set of physical and virtual resources.
+
+**3.1.3 multi-tenancy** [ITU-T Y.3500]: Allocation of physical or virtual resources such that multiple tenants and their computations and data are isolated from and inaccessible to one another.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 distributed system:** A system composed of several computers connected by the network. Different computers transmit information through the network for communication and cooperation related to computing tasks.
+
+- 3.2.2 batch computing:** The process of automatically process stored data in units of data sets.
+- 3.2.3 distributed computing:** The invention relates to a computing mode involving a storage layer and a processing layer for implementing a multi-type programming algorithm model.
+- 3.2.4 distributed data processing:** The process of distributing data operations to each node of a computer network for performing calculation.
+- 3.2.5 distributed file system:** The file management system distributed on multiple nodes that can be managed, and the communication and data transmission between nodes that can be carried out through the network in the distributed system.
+- 3.2.6 NoSQL database:** The general name of non-relational database management system, including key values, columns, file, and graph database management system and so on. In a non-relational database management system, data is not organized in a relational model.
+- 3.2.7 scale out:** The process of using an integrated group of individual resources as a single system.
+- 3.2.8 streaming data:** Data generated from a continuously running data source through an interface.
+- 3.2.9 structured data:** A data representation in which the structure of each record assembled from data elements is consistent and can be effectively described using a relational model.
+- 3.2.10 unstructured data:** Data that does not have a predefined model or is not organized in a defined manner.
+
+## 4 Abbreviations and acronyms
+
+This Recommendations uses the following abbreviations and acronyms:
+
+|       |                            |
+|-------|----------------------------|
+| JDBC  | Java Database Connectivity |
+| NoSQL | Not Only SQL               |
+| ODBC  | Open Database Connectivity |
+| SQL   | Structural Query Language  |
+
+## 5 Conventions
+
+In this Recommendation, the following conventions are used:
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement needs not be present to claim conformance.
+- The keywords "can optionally" and "may" indicate an optional requirement which is permissible, without implying any sense of being recommended. These terms are not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Overview
+
+Big data infrastructure is a software service based on a distributed system. It can store many types of data, through the distributed system to complete the rapid processing of the data, so as to support the implementation of the upper data application. At the same time, it also has the ability of operation, security management and resource scheduling. The reference framework shown in Figure 1 is
+
+required to include functions like: distributed storage, batch computing, SQL engine, resource scheduling, operation, and security management.
+
+It is recommended for the reference framework to contain NoSQL databases.
+
+![Figure 1: Big data infrastructure reference framework diagram. The diagram shows a layered architecture. At the top is 'Applications'. Below it is a large box labeled 'Big data infrastructure' which contains a dashed box with 'SQL engine', 'NoSQL databases', 'Batch computing', and 'Distributed storage'. To the left of this dashed box is 'Resource scheduling' and to the right is 'Operation/security management'. At the bottom is a 'Data' layer with boxes for 'TEXT', 'IMAGE', 'VIDEO', 'CSV', and '...'. Double-headed arrows connect 'Applications' to the 'Big data infrastructure' box, the 'Big data infrastructure' box to the 'Data' layer, and various components within the 'Big data infrastructure' box. A label 'F.743.20(20)_F01' is at the bottom right.](562f471e8153729557e6a4ee6343c32c_img.jpg)
+
+Figure 1: Big data infrastructure reference framework diagram. The diagram shows a layered architecture. At the top is 'Applications'. Below it is a large box labeled 'Big data infrastructure' which contains a dashed box with 'SQL engine', 'NoSQL databases', 'Batch computing', and 'Distributed storage'. To the left of this dashed box is 'Resource scheduling' and to the right is 'Operation/security management'. At the bottom is a 'Data' layer with boxes for 'TEXT', 'IMAGE', 'VIDEO', 'CSV', and '...'. Double-headed arrows connect 'Applications' to the 'Big data infrastructure' box, the 'Big data infrastructure' box to the 'Data' layer, and various components within the 'Big data infrastructure' box. A label 'F.743.20(20)\_F01' is at the bottom right.
+
+**Figure 1 – Big data infrastructure reference framework**
+
+In order to ensure the successful implementation of big data application, it is necessary to establish the assessment framework of big data infrastructure taking into account six aspects, so as to verify the capability range of big data infrastructure. These six aspects shown in Figure 2 are the metrics such as function metrics, performance metrics, scalability metrics, security metrics, operation metrics and compatibility metrics.
+
+![Figure 2: Metrics for big data infrastructure assessments diagram. A central circle is labeled 'Big data infrastructure'. Six arrows point outwards from this circle to labels: 'Function metrics' (top), 'Performance metrics' (top-right), 'Scalability metrics' (right), 'Security metrics' (bottom), 'Operation metrics' (bottom-left), and 'Compatibility metrics' (top-left). A label 'F.743.20(20)_F02' is at the bottom right.](367926125450c2bc3f4bdca9d59a62ba_img.jpg)
+
+Figure 2: Metrics for big data infrastructure assessments diagram. A central circle is labeled 'Big data infrastructure'. Six arrows point outwards from this circle to labels: 'Function metrics' (top), 'Performance metrics' (top-right), 'Scalability metrics' (right), 'Security metrics' (bottom), 'Operation metrics' (bottom-left), and 'Compatibility metrics' (top-left). A label 'F.743.20(20)\_F02' is at the bottom right.
+
+**Figure 2 – Metrics for big data infrastructure assessments**
+
+## 7 Function metrics
+
+Big data infrastructure is required to have basic functions to process data, including:
+
+- Data import: The infrastructure is required to support data loading from an external data source into distributed storage.
+
+- Data storage: The infrastructure is required to support distributed storage of massive data, provide multi-copy storage capacity, be able to achieve high data storage persistence, and support a variety of data formats and compression algorithms.
+- Batch computing: The infrastructure is required to support data processing in units of data sets, which include data transformations and data analysis.
+
+Big data infrastructure is recommended to have other functions to process data, including:
+
+- Streaming data import: The infrastructure is recommended to support streaming data loading from an external data source into distributed storage and import tasks can be executed in a scheduled manner or immediately.
+- Streaming data processing: The infrastructure is recommended to support real-time data processing, where the data is continuous and boundless and can be processed item by item.
+- Data storage management: The infrastructure is recommended to support management of data storage, where data can be classified according to the user-defined policy.
+
+## 8 Performance metrics
+
+Big data infrastructure is recommended to meet the performance requirements of distributed systems [ITU-T Q.3930]. It is recommended to disclose the details of the performance indicators including:
+
+- Effective storage space: The infrastructure is recommended to disclose the effective storage space and measurement of this indicator.
+- Batch task execution time: The infrastructure is recommended to disclose the execution time and test environment of a batch task in a particular scenario.
+
+If a big data infrastructure provides NoSQL databases, it is recommended to disclose read-write performance and a test environment of NoSQL databases in the particular scenario.
+
+## 9 Scalability metrics
+
+Big data infrastructure is required to have the ability of online horizontal expansion. The performance increases while the number of nodes increases.
+
+Big data infrastructure is recommended to have the ability of on-line horizontal shrinkage.
+
+## 10 Security metrics
+
+Big data infrastructure is required to have security protection to prevent malicious access and attacks, which includes:
+
+- Identity authentication: The infrastructure is required to identify different users.
+- Authority management: The infrastructure is required to support authority management with different roles and systems.
+- Data encryption and decryption: The infrastructure is required to support data encryption and decryption in multiple ways.
+- Audit: The infrastructure is required to support logging audit with different operations.
+
+## 11 Operation metrics
+
+Big data infrastructure is required to have operation management capabilities, which includes:
+
+- Deployment capabilities: The infrastructure is required to support automatic deployment with a visual interface.
+- Cluster management: The infrastructure is required to support operation on clusters with a visual interface.
+
+- User management: The infrastructure is required to support creation, modification and deletion of users and user groups, assignment of different roles and permissions, and modification of user passwords and user information.
+- Fault management: The infrastructure is required to support distinction of alarm levels, configuration of alarm thresholds, and alarm notification through visual interfaces, e-mail, or SMS.
+- Resource monitoring: The infrastructure is required to support visual resource monitoring to check the software and hardware configuration, system performance and resource usage of each module of the system.
+- Job monitoring: The infrastructure is required to support visual monitoring of status, resource usage and log information on jobs.
+- Configuration management: The infrastructure is required to support configuration of a system, including configuration viewing and modification.
+- Log management: The infrastructure is required to support viewing, retrieving, and downloading the logs of the system.
+- Upgrade: The infrastructure is required to support software upgrade without downtime.
+- Multi-tenancy management: The infrastructure is required to support the ability to allocate and schedule computing resources for multiple different tenants and ensure that computing resources for different tenants are isolated from each other.
+
+## **12 Compatibility metrics**
+
+Big data infrastructure is required to support a development interface for applications, which includes:
+
+- Interfaces for JDBC and ODBC.
+- Support for SQL syntax, including data types, operators, functions, etc.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.743.26-202406-I_PDF-E/raw.md

@@ -0,0 +1,359 @@
+
+
+# Recommendation **ITU-T F.743.26 (06/2024)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+## **Technical requirements of cloud gaming platform based on IMT-2020 mobile edge computing**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font overlaid on the globe.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.743.26
+
+# Technical requirements of cloud gaming platform based on IMT-2020 mobile edge computing
+
+## Summary
+
+Recommendation ITU-T F.743.26 specifies the technical requirements of cloud gaming platform based on IMT-2020 mobile edge computing. It defines the deployment, technical requirements for operations functionality within the cloud gaming platform, technical requirements for service capability functionality within the cloud gaming platform, technical requirements for cloud computing platform and network, and security requirements. The Recommendation aims to utilize the technical advantages of IMT-2020 mobile edge computing to provide a reference for the development and deployment of the cloud gaming platform.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.743.26 | 2024-06-13 | 16          | 11.1002/1000/15906 |
+
+## Keywords
+
+Central cloud, cloud gaming platform, deployment, edge cloud, mobile edge computing.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2024
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                      | Page |
+|------------------------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                                        | 1    |
+| 2 References.....                                                                                    | 1    |
+| 3 Definitions .....                                                                                  | 1    |
+| 3.1 Terms defined elsewhere .....                                                                    | 1    |
+| 3.2 Terms defined in this Recommendation.....                                                        | 2    |
+| 4 Abbreviations and acronyms .....                                                                   | 2    |
+| 5 Conventions .....                                                                                  | 3    |
+| 6 Overview .....                                                                                     | 3    |
+| 7 Cloud gaming platform deployment.....                                                              | 4    |
+| 7.1 Cloud gaming platform deployment based on MEC.....                                               | 4    |
+| 7.2 Cloud gaming platform deployment based on public cloud sinking.....                              | 5    |
+| 8 Technical requirements for service capability functionality within the cloud gaming platform ..... | 5    |
+| 9 Technical requirements for operations functionality within the cloud gaming platform .....         | 6    |
+| 10 Technical requirements for cloud computing platform and network .....                             | 6    |
+| 10.1 Technical requirements for central cloud .....                                                  | 6    |
+| 10.2 Technical requirements for edge cloud .....                                                     | 6    |
+| 10.3 Technical requirements for traffic diversion based on MEC .....                                 | 7    |
+| 10.4 Technical requirements for traffic diversion based on public cloud sinking .                    | 7    |
+| 11 Security requirements .....                                                                       | 7    |
+| Bibliography.....                                                                                    | 8    |
+
+
+
+# Technical requirements of cloud gaming platform based on IMT-2020 mobile edge computing
+
+# 1 Scope
+
+This Recommendation describes the technical requirements of cloud gaming platform based on international mobile telecommunications for 2020 (IMT-2020) mobile edge computing.
+
+The scope of this Recommendation includes:
+
+- Cloud gaming platform deployment.
+- Technical requirements for operations functionality within the cloud gaming platform.
+- Technical requirements for service capability functionality within the cloud gaming platform.
+- Technical requirements for cloud computing platform and network.
+- Security requirements.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T F.743.17] Recommendation ITU-T F.743.17 (2022), *Requirements for cloud gaming systems*.
+- [ITU-T X.1815] Recommendation ITU-T X.1815 (2023), *Security guidelines and requirements for IMT-2020 edge computing services*.
+- [3GPP TS 23.501] 3GPP TS 23.501 V18.5.0 (2024), *System Architecture for the 5G System (5GS); Stage 2 (Release 18)*.
+- [ETSI GS MEC 003] ETSI GS MEC 003 V3.2.1 (2024), *Multi-Access Edge Computing (MEC); Framework and Reference Architecture*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 cloud gaming** [ITU-T F.743.17]: A way of playing the game on a cloud server. In the "cloud gaming" mode, game storage, computing, rendering, and so on are completed in the cloud, players can experience high-quality games through any terminal, anytime anywhere.
+
+**3.1.2 cloud computing** [b-ITU-T Y.3500]: Paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand.
+
+**3.1.3 cloud service** [b-ITU-T Y.3500]: One or more capabilities offered via cloud computing (3.1.2) invoked using a defined interface.
+
+**3.1.4 IMT-2020** [b-ITU-T Y.3100]: (Based on [b-ITU-R M.2083]) Systems, system components, and related technologies that provide far more enhanced capabilities than those described in [b-ITU-R M.1645].
+
+**3.1.5 IMT-2020 system** [ITU-T X.1815]: 3GPP system consisting of the IMT-2020 access network (AN), IMT-2020 core network and user equipment (UE).
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+**3.2.1 cloud gaming instance:** A virtual machine instance that contains the necessary environment for one game to run in the cloud, including central processing unit (CPU), graphic processing unit (GPU), memory, storage and network.
+
+**3.2.2 executable game:** The game package which is generated after installing a game on a virtual machine, including program files, resource files, configuration files and other essential components for the game to run.
+
+**3.2.3 game cloudification:** The process and technology that involve uploading a game from local storage to a cloud gaming instance, generating an executable game, and uploading it to the file server for distribution across multiple edge cloud nodes.
+
+**3.2.4 public cloud sinking:** A process that involves transferring cloud computing resources from the central cloud to edge nodes that are located closer to users.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|          |                                                  |
+|----------|--------------------------------------------------|
+| AAC      | Advanced Audio Coding                            |
+| AN       | Access Network                                   |
+| CGS      | Cloud Gaming Service                             |
+| CPU      | Central Processing Unit                          |
+| GPU      | Graphic Processing Unit                          |
+| IMT-2020 | International Mobile Telecommunications for 2020 |
+| MEC      | Multi-access Edge Computing                      |
+| MEO      | MEC Orchestrator                                 |
+| MEP      | MEC Platform                                     |
+| MEPM     | MEP Manager                                      |
+| NEF      | Network Exposure Function                        |
+| OSS      | Operations Support System                        |
+| PCF      | Policy Control Function                          |
+| QoS      | Quality of Service                               |
+| (R)AN    | (Radio) Access Network                           |
+| UE       | User Equipment                                   |
+| UPF      | User Plane Function                              |
+| VIM      | Virtualization Infrastructure Manager            |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "is required" indicate a requirement which must be strictly followed and from which no deviation is permitted if the conformance to this document is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but not absolutely required. Thus, this requirement needn't be present to claim conformance.
+
+Requirements are identified using the following conventions:
+
+- Requirement number xx in clause n is of the form R-n-xx.
+- Recommended requirement number yy in clause n is of the form RR-n-yy.
+- Requirement number xx in subclause n.m is of the form R-n.m-xx.
+- Recommended requirement number yy in subclause n.m is of the form RR-n.m-yy.
+
+# 6 Overview
+
+This Recommendation specifies the content shown in the right part of Figure 1, and it mainly references the content within the red dashed box, which is based on [ITU-T F.743.17]. To enhance the user experience, improve operational efficiency, and increase flexibility, it is essential to specify the requirements of operations functionality and service capability functionality within the cloud gaming platform. The cloud gaming platform includes, but is not limited to, these two functionalities. The other functionalities are beyond the scope of this Recommendation. In the Recommendation, the network specifically refers to the IMT-2020 network.
+
+![Figure 1: Functionality of cloud gaming platform based on IMT-2020 mobile edge computing. The diagram shows a hierarchy of components. At the top is the 'Cloud gaming user'. Below it, 'Cloud gaming service provider' and 'Cloud gaming developer' are grouped under 'CGS'. Arrows show 'Game distribution' from CGS to the user, 'Basic ability' from the platform provider to the service provider, and 'Game content' from the developer to the platform provider. The 'Cloud gaming platform provider' is in a red dashed box and receives 'Infrastructure' from the 'Cloud computing platform and network' at the bottom. To the right, a detailed view of the 'Cloud gaming platform' shows 'Service capability functionality' (Rendering, Encoding, Streaming) and 'Operations functionality' (Instances management, Archives management, Games management, Scheduling management, and ellipsis).](a234352dfaccdc24745c88eef7724cc6_img.jpg)
+
+The diagram illustrates the functional architecture of a cloud gaming platform. At the top, the 'Cloud gaming user' interacts with the 'Cloud gaming service provider' and 'Cloud gaming developer' (collectively labeled 'CGS') via 'Game distribution'. The 'Cloud gaming service provider' receives 'Basic ability' from the 'Cloud gaming platform provider', while the 'Cloud gaming developer' provides 'Game content' to it. The 'Cloud gaming platform provider' is supported by 'Infrastructure' from the 'Cloud computing platform and network'. A red dashed box highlights the 'Cloud gaming platform provider' and its associated 'Cloud gaming service provider' and 'Cloud gaming developer'. To the right, a detailed view of the 'Cloud gaming platform' shows two main functional areas: 'Service capability functionality' (which includes Rendering, Encoding, and Streaming) and 'Operations functionality' (which includes Instances management, Archives management, Games management, Scheduling management, and other functions indicated by an ellipsis). The entire platform is supported by the 'Cloud computing platform and IMT-2020 based network' at the base.
+
+Figure 1: Functionality of cloud gaming platform based on IMT-2020 mobile edge computing. The diagram shows a hierarchy of components. At the top is the 'Cloud gaming user'. Below it, 'Cloud gaming service provider' and 'Cloud gaming developer' are grouped under 'CGS'. Arrows show 'Game distribution' from CGS to the user, 'Basic ability' from the platform provider to the service provider, and 'Game content' from the developer to the platform provider. The 'Cloud gaming platform provider' is in a red dashed box and receives 'Infrastructure' from the 'Cloud computing platform and network' at the bottom. To the right, a detailed view of the 'Cloud gaming platform' shows 'Service capability functionality' (Rendering, Encoding, Streaming) and 'Operations functionality' (Instances management, Archives management, Games management, Scheduling management, and ellipsis).
+
+**Figure 1 – Functionality of cloud gaming platform based on IMT-2020 mobile edge computing**
+
+The service capability functionality needs to support rendering, encoding and streaming. The rendering capability refers to rendering game content into images. The encoding capability involves encoding the rendered images and audio data. The streaming capability refers to transmitting the encoded stream to the user's device.
+
+The operations functionality includes instances management, games management, archives management, and scheduling management. Instances management is responsible for managing the status and allocation of cloud gaming instances. Games management is responsible for game cloudification and updates. Archives management is responsible for managing user game progress and data. Scheduling management is responsible for providing a range of scheduling strategies and allocating appropriate cloud gaming instances based on these scheduling strategies.
+
+The cloud computing platform typically provides both central and edge cloud services. The service capability functionality is deployed at the network edge, with a focus on crucial technologies that directly impact gaming performance. The operations functionality is deployed in a centralized location to primarily handle operational tasks and improve overall management efficiency.
+
+IMT-2020 network provides traffic diversion. The cloud gaming platform utilizes this capability to schedule game users to appropriate edge cloud nodes, thereby enhancing gaming performance and user experience.
+
+# 7 Cloud gaming platform deployment
+
+## 7.1 Cloud gaming platform deployment based on multi-access edge computing (MEC)
+
+The cloud gaming platform deployment, which is based on multi-access edge computing (MEC), is shown in Figure 2. The left part of the deployment mainly references the IMT-2020 system based on [3GPP TS 23.501], while the right part follows the MEC system defined in [ETSI GS MEC 003].
+
+![Figure 2: Cloud gaming platform deployment based on MEC. The diagram shows the architecture of the cloud gaming platform. On the left, the IMT-2020 core network (containing NEF, PCF, and UPF) is connected to a UE via an (R)AN. The core network connects to the MEC system through reference points N33, N5, and N6. The MEC system contains the following functional elements: OSS (Operations functionality), MEO, MEC host (Service capability functionality, MEP, and Virtualization infrastructure), MEPM, and VIM. Reference points Mm1 through Mm7 are shown between these elements. Mm1 is between OSS and MEO; Mm2 is between OSS and MEPM; Mm3 is between MEO and MEPM; Mm4 is between MEO and VIM; Mm5 is between Service capability functionality and MEPM; Mp1 is between Service capability functionality and MEP; Mm6 is between MEPM and VIM; and Mm7 is between Virtualization infrastructure and VIM. A label F.743.26(24) is present at the bottom right of the diagram.](053f1077d592e6622cd21dc4bb4cb366_img.jpg)
+
+Figure 2: Cloud gaming platform deployment based on MEC. The diagram shows the architecture of the cloud gaming platform. On the left, the IMT-2020 core network (containing NEF, PCF, and UPF) is connected to a UE via an (R)AN. The core network connects to the MEC system through reference points N33, N5, and N6. The MEC system contains the following functional elements: OSS (Operations functionality), MEO, MEC host (Service capability functionality, MEP, and Virtualization infrastructure), MEPM, and VIM. Reference points Mm1 through Mm7 are shown between these elements. Mm1 is between OSS and MEO; Mm2 is between OSS and MEPM; Mm3 is between MEO and MEPM; Mm4 is between MEO and VIM; Mm5 is between Service capability functionality and MEPM; Mp1 is between Service capability functionality and MEP; Mm6 is between MEPM and VIM; and Mm7 is between Virtualization infrastructure and VIM. A label F.743.26(24) is present at the bottom right of the diagram.
+
+Figure 2 – Cloud gaming platform deployment based on MEC
+
+The MEC system contains the following functional elements: MEC host, operation support system (OSS), MEC orchestrator (MEO), virtualization infrastructure manager (VIM), MEC platform (MEP) manager (MEPM) and the reference points between them. These functional elements are specified in [ETSI GS MEC 003]. The operations functionality is deployed in the OSS. The service capability functionality is deployed in the MEC host, and the MEP within the host provides support through the Mp1 reference point to ensure running of cloud gaming. The MEC host contains MEC platform (MEP) and virtualization infrastructure. In terms of deployment location, MEPM can be deployed together with MEC host on the edge or with network element in a relatively centralized location.
+
+The user plane function (UPF) can be flexibly deployed on the network edge, while the policy control function (PCF) can be centrally deployed. UPF implements the data plane function of IMT-2020 edge computing, and the MEC host provides the operating environment for the cloud gaming platform. Depending on the application scenario, the UPF and MEC host can be deployed separately or together.
+
+The MEC system and the UPF are connected through the N6 [3GPP TS 23.501] interface, which enables data transmission between them. The implementation of cloud gaming utilizes IMT-2020 network capabilities, general information technology capabilities and industry-specific capabilities through the Mp1 [ETSI GS MEC 003] interface. The MEC system requires two additional interactions with the IMT-2020 network. The first one is an interaction with PCF through the N5 [3GPP TS 23.501] interface, and the second one is an interaction with the network exposure function (NEF) through the N33 [3GPP TS 23.501] interface.
+
+The user equipment (UE) contains all terminals that run cloud gaming and are connected to IMT-2020 core network via the (radio) access network ((R)AN). The (R)AN is the wireless access layer that manages wireless communication connections. The UPF is connected to the (R)AN and is responsible for processing game data transmitted by cloud gaming terminals.
+
+## 7.2 Cloud gaming platform deployment based on public cloud sinking
+
+The deployment of the cloud gaming platform based on public cloud sinking is shown in Figure 3. The left part is based on the IMT-2020 system, which is mainly defined by 3GPP. The right side is based on public cloud sinking. The operations functionality is deployed in the central cloud. Additionally, the service capability functionality is deployed in the edge cloud. The central cloud and the edge cloud interact and collaborate through the network.
+
+![Diagram of cloud gaming platform deployment based on public cloud sinking. The diagram shows three main components: UE, (R)AN, and IMT-2020 core network on the left, and Edge cloud and Central cloud on the right. The UE is connected to the (R)AN, which is connected to the IMT-2020 core network. The IMT-2020 core network contains NEF, PCF, and UPF. The UPF is connected to the Edge cloud via the N6 interface. The NEF is connected to the Edge cloud via the N33 interface. The Edge cloud contains Service capability functionality, Edge cloud service, and Edge cloud infrastructure. The Central cloud contains Operations functionality, Central cloud service, and Central cloud infrastructure. The Edge cloud and Central cloud are connected to each other.](7e670a2b556b53ea9002dfff3a420e08_img.jpg)
+
+The diagram illustrates the architecture for cloud gaming platform deployment based on public cloud sinking. On the far left, the User Equipment (UE) is connected to the (Radio) Access Network ((R)AN). The (R)AN is connected to the IMT-2020 core network. Inside the IMT-2020 core network, there are three main components: Network Exposure Function (NEF), Policy Control Function (PCF), and User Plane Function (UPF). The UPF is connected to the Edge cloud via the N6 interface. The NEF is connected to the Edge cloud via the N33 interface. The Edge cloud is a large box containing three sub-components: Service capability functionality, Edge cloud service, and Edge cloud infrastructure. To the right of the Edge cloud is the Central cloud, which also contains three sub-components: Operations functionality, Central cloud service, and Central cloud infrastructure. A horizontal line connects the Edge cloud and the Central cloud, indicating their interaction. At the bottom right of the diagram, there is a label 'F.743.26(24)'.
+
+Diagram of cloud gaming platform deployment based on public cloud sinking. The diagram shows three main components: UE, (R)AN, and IMT-2020 core network on the left, and Edge cloud and Central cloud on the right. The UE is connected to the (R)AN, which is connected to the IMT-2020 core network. The IMT-2020 core network contains NEF, PCF, and UPF. The UPF is connected to the Edge cloud via the N6 interface. The NEF is connected to the Edge cloud via the N33 interface. The Edge cloud contains Service capability functionality, Edge cloud service, and Edge cloud infrastructure. The Central cloud contains Operations functionality, Central cloud service, and Central cloud infrastructure. The Edge cloud and Central cloud are connected to each other.
+
+**Figure 3 – Cloud gaming platform deployment based on public cloud sinking**
+
+The edge cloud exchanges data with the UPF through the N6 interface. The only way for the edge cloud to access the capabilities of the IMT-2020 network is to interact with NEF through the N33 interface.
+
+# 8 Technical requirements for service capability functionality within the cloud gaming platform
+
+- R-8-01: The service capability functionality is required to support game rendering. This functionality can perform operations and graphics rendering in the cloud and generate real-time game video streams.
+
+- R-8-02: The service capability functionality is required to support encoding. This functionality should provide multiple audio and video codec capabilities, such as advanced audio coding (AAC) [b-ISO/IEC 13818-7], H.264 [b-ITU-T H.264], etc. Additionally, the codec configuration should be adjustable based on operational strategy, terminal user settings and network transmission quality.
+- R-8-03: The service capability functionality is required to support streaming media transmission technology. During data transmission, this functionality has the capability to automatically adjust audio and video encoding bit rates, network bandwidth and packet strategies.
+- RR-8-01: The service capability functionality is recommended to support basic strategies for mitigating weak network conditions to ensure a high-quality gaming experience. This functionality needs to balance factors such as image quality and smoothness, while optimizing for network issues like packet loss, jitter and delay.
+
+# **9 Technical requirements for operations functionality within the cloud gaming platform**
+
+- R-9-01: The operations functionality is required to manage the state of cloud gaming instances and their transitions. This platform should allocate idle cloud gaming instances based on user requests.
+- R-9-02: The operations functionality is required to support dynamic allocation of cloud gaming instance types. This platform should allocate suitable edge cloud instance types based on different business requirements.
+- R-9-03: The operations functionality is required to support a variety of scheduling strategies, including load balancing, geographical location and historical record.
+- R-9-04: The operations functionality is required to support game cloudification.
+- R-9-05: The operations functionality is required to support regular checks for game version updates. If updates are available, the updated game will be cloudified again.
+- R-9-06: The operations functionality is required to provide interfaces for uploading game archives of users, downloading saved archives, and querying archive status.
+- RR-9-01: The operations functionality is recommended to support the unified management archive for users on various terminal devices, which enables the storage, backup and retrieval of game archives.
+
+# **10 Technical requirements for cloud computing platform and network**
+
+## **10.1 Technical requirements for central cloud**
+
+- R-10.1-01: The central cloud is required to support the unified management of edge cloud nodes and dynamically adjust different types of edge cloud nodes based on regional demands.
+- R-10.1-02: The central cloud is required to support dynamic allocation of edge cloud. The central cloud accepts the request from the user and schedules it to the appropriate edge cloud.
+- RR-10.1-01: The central cloud is recommended to support overall resource management, edge business arrangement, the centralized operation and maintenance.
+
+## **10.2 Technical requirements for edge cloud**
+
+- R-10.2-01: Each edge cloud is required to cover one or more cities. For megacities and cities with mass users, multiple edge clouds can be built.
+- R-10.2-02: The edge cloud is required to support network access and be able to connect to the IMT-2020 network at a minimum.
+
+- RR-10.2-01: The edge cloud is recommended to have the network access capability of multiple telecom carriers.
+- RR-10.2-02: The edge cloud is recommended to support the reuse of computing power. When edge cloud resources are idle, their computing power can be shared with users in other scenarios, thus reducing construction costs.
+
+## **10.3 Technical requirements for traffic diversion based on MEC**
+
+- R-10.3-01: Traffic diversion is required to be implemented through the MEC platform.
+- R-10.3-02: When game users switch between MEC services, the MEO is required to perform context migration and inform the cloud gaming platform to switch service nodes.
+- RR-10.3-01: The wireless bandwidth and latency are recommended to be guaranteed by using quality of service (QoS), which can be invoked through the N5 or N33 interfaces.
+
+## **10.4 Technical requirements for traffic diversion based on public cloud sinking**
+
+- R-10.4-01: Traffic diversion is required to be implemented to access the IMT-2020 core network capabilities through the N33 interface.
+- R-10.4-02: When game users migrate between edge cloud nodes, the cloud gaming platform itself is required to detect the migration and implement it to access the IMT-2020 core network capabilities through the N33 interface.
+- RR-10.4-01: The wireless bandwidth and latency are recommended to be guaranteed by using QoS through the N33 interface.
+
+# **11 Security requirements**
+
+The security requirements for IMT-2020 edge computing services specified in [ITU-T X.1815], including those for the infrastructure layer, the network layer, and the edge application layer, are applicable to this Recommendation.
+
+## Bibliography
+
+- [b-ITU-T H.264] Recommendation ITU-T H.264 (2024), *Advanced video coding for generic audiovisual services.*
+- [b-ITU-T Y.3100] Recommendation ITU-T Y.3100 (2017), *Terms and definitions for IMT-2020 network.*
+- [b-ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014), *Information technology – Cloud computing – Overview and vocabulary.*
+- [b-ITU-R M.1645] Recommendation ITU-R M.1645 (2003), *Framework and overall objectives of the future development of IMT-2000 and systems beyond IMT-2000.*
+- [b-ITU-R M.2083] Recommendation ITU-R M.2083 (2015), *IMT Vision – Framework and overall objectives of the future development of IMT for 2020 and beyond.*
+- [b-ISO/IEC 13818-7] ISO/IEC 13818-7 (2006), *Information technology – Generic coding of moving pictures and associated audio information – Part 7: Advanced Audio Coding (AAC).*
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,507 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.4**
+
+(03/2017)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Functional requirements for virtual content  
+delivery networks**
+
+Recommendation ITU-T F.743.4
+
+ITU-T
+
+![ITU logo: A globe with a red lightning bolt, next to the text 'International Telecommunication Union'.](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in a blue, sans-serif font.
+
+ITU logo: A globe with a red lightning bolt, next to the text 'International Telecommunication Union'.
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.743.4
+
+# Functional requirements for virtual content delivery networks
+
+## Summary
+
+Recommendation ITU-T F.743.4 gives an overview and the requirements for a virtual content delivery network (VCDN). Appendix I provides two use cases to show how to apply VCDN scenario.
+
+Compared with the traditional content delivery network (CDN) service provisioning defined in Recommendations ITU-T Y.1901 and ITU-T Y.2019, VCDN is a new paradigm using cloud computing, network virtualization and software defined networking (SDN) technology for content delivery for various multimedia services, providing a CDN infrastructure according to vendors' needs. This Recommendation specifies the requirements for VCDN, including requirements on service provision, physical resource management, virtual resource management, VCDN logically isolated network partition (LINP) management, service management, backbone network and security consideration.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.4  | 2017-03-01 | 16          | <a href="http://handle.itu.int/11.1002/1000/13178">11.1002/1000/13178</a> |
+
+## Keywords
+
+Cloud computing, content delivery network, SDN, streaming service, virtualisation.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2017
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                        | Page |
+|------------------------------------------------------------------------|------|
+| 1 Scope.....                                                           | 1    |
+| 2 References.....                                                      | 1    |
+| 3 Definitions .....                                                    | 1    |
+| 3.1 Terms defined elsewhere .....                                      | 1    |
+| 3.2 Terms defined within this Recommendation.....                      | 2    |
+| 4 Abbreviations and acronyms .....                                     | 2    |
+| 5 Conventions .....                                                    | 2    |
+| 6 Background.....                                                      | 2    |
+| 7 Overview of VCDN .....                                               | 3    |
+| 8 Objectives .....                                                     | 4    |
+| 9 Requirements .....                                                   | 4    |
+| 9.1 Service provision requirements .....                               | 4    |
+| 9.2 Physical resource management requirements.....                     | 5    |
+| 9.3 Virtual resource requirements .....                                | 5    |
+| 9.4 VCDN LINP requirements .....                                       | 7    |
+| 9.5 Service management requirements.....                               | 8    |
+| 10 Backbone network requirements .....                                 | 9    |
+| 11 Security considerations .....                                       | 9    |
+| Appendix I – Use cases for VCDN .....                                  | 11   |
+| I.1 Use case 1: the number of users is rapidly rising in one area..... | 11   |
+| I.2 Use case 2: one node is broken.....                                | 12   |
+| Bibliography.....                                                      | 14   |
+
+
+
+# Recommendation ITU-T F.743.4
+
+## Functional requirements for virtual content delivery networks
+
+## 1 Scope
+
+This Recommendation describes the functional requirements for a virtual content delivery network (VCDN). The scope of this Recommendation covers:
+
+- An overview of VCDN concept and the objectives of VCDN.
+- The requirements for applying VCDN on service provision, all kinds of resources of VCDN, and security considerations.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T Y.1901] Recommendation ITU-T Y.1901 (2009), *Requirements for the support of IPTV services*.
+- [ITU-T Y.2019] Recommendation ITU-T Y.2019 (2010), *Content delivery functional architecture in NGN*.
+- [ITU-T Y.3011] Recommendation ITU-T Y.3011 (2012), *Framework of network virtualization for future networks*.
+- [ITU-T Y.3300] Recommendation ITU-T Y.3300 (2014), *Framework of software-defined networking*.
+- [ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014) *Information technology – Cloud computing – Overview and vocabulary*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 logically isolated network partition (LINP)** [ITU-T Y.3011]: A network that is composed of multiple virtual resources which is isolated from other LINPs.
+
+**3.1.2 network virtualization** [ITU-T Y.3011]: A technology that enables the creation of logically isolated network partitions over shared physical networks so that heterogeneous collection of multiple virtual networks can simultaneously coexist over the shared networks. This includes the aggregation of multiple resources in a provider and appearing as a single resource.
+
+**3.1.3 virtual resource** [ITU-T Y.3011]: An abstraction of physical or logical resource, which may have different characteristics from the physical or logical resource and whose capability may be not bound to the capability of the physical or logical resource.
+
+**3.1.4 software-defined networking** [ITU-T Y.3300]: A set of techniques that enables to directly program, orchestrate, control and manage network resources, which facilitates the design, delivery and operation of network services in a dynamic and scalable manner.
+
+**3.1.5 cloud computing** [ITU-T Y.3500]: Paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand.
+
+### 3.2 Terms defined within this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 virtual content delivery network**: A content delivery network using virtualisation technology that enables the allocation of virtual storage, virtual machines, and network resources according to vendors' requirements in a dynamic and scalable manner.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                               |
+|------|-----------------------------------------------|
+| AAA  | Authentication, Authorization, and Accounting |
+| ACL  | Access Control List                           |
+| CPU  | Central Processing Unit                       |
+| I/O  | Input/Output                                  |
+| LINP | Logically Isolated Network Partition          |
+| OS   | Operating System                              |
+| QoS  | Quality of Service                            |
+| SDN  | Software Defined Networking                   |
+| SLA  | Service Level Agreement                       |
+| VCDN | Virtual Content Delivery Network              |
+| VLAN | Virtual Local Area Network                    |
+
+## 5 Conventions
+
+In this Recommendation, the following conventions are used:
+
+- The keywords "is required" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+- The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Background
+
+With the development of Internet technology, the network traffic resulting from audio and video services grows exponentially. In the future Internet, video services will be mainstream. A content delivery network (CDN) is technically a comprehensive solution to handle the increased demand for
+
+services. Existing CDN architectures face the challenges of a dramatic increase in video service traffic, as well as additional construction and maintenance costs provided to various multi-vendor services. How to sufficiently take advantage of the resource of CDN to provide flexible and superior service is an important issue to be resolved.
+
+The essential character of virtualisation technology is the elastic allocation of resources. A virtual content distribution network (VCDN) uses virtualization technology to make a unified resource pool, to provide the infrastructure of CDN according to the vendors' need. VCDN uses the management interface to monitor CDNs' load.
+
+VCDN can realize accurate infrastructure distribution and elastic resource scheduling. VCDN can integrate the resources of CDN, reduce construction cost and improve the scalability.
+
+## 7 Overview of VCDN
+
+Virtual CDN provides content delivery service to multiple vendors. VCDN utilizes a set of techniques including cloud computing, network virtualization and software defined networking (SDN) to dynamically control and manage the computing and network resources, which improves scalability, flexibility and availability.
+
+Figure 1 illustrates the basic concept of VCDN.
+
+![Diagram illustrating the VCDN concept, showing layers for LINP management, Resource management, Network controller, and the underlying physical and virtual resource layers across multiple nodes.](dbe553cf16dd14073b89a8263a428664_img.jpg)
+
+The diagram illustrates the VCDN concept across several layers. At the top, three colored ovals represent LINP 1 (blue), LINP 2 (red), and LINP 3 (yellow). Below this, two nodes, Node 1 and Node 2, are shown. Each node contains a 'Logical isolation' layer with colored ovals, a 'Virtual resource' layer with server icons, and a 'Physical resource' layer with server icons. On the left, three management boxes—'LINP management', 'Resource management', and 'Network controller'—are connected via double-headed arrows to the corresponding layers. At the bottom, a 'Backbone network' consisting of several switches is connected to 'End users' (represented by computer icons) through both nodes. The diagram is labeled F.743.4(17)\_F01 in the bottom right corner.
+
+Diagram illustrating the VCDN concept, showing layers for LINP management, Resource management, Network controller, and the underlying physical and virtual resource layers across multiple nodes.
+
+Figure 1 – VCDN concept
+
+A typical CDN providing good performance content delivery service generally consists of many nodes which are located in different areas close to the end user. The nodes are deployed as physical resources such as servers, storage and switches. The physical resources are converted into virtual
+
+resources such as virtual machines, virtual storage and virtual switches, which form a virtual resources pool utilizing virtualization technology. In order to provide service to multiple vendors in a single physical CDN, virtual resources are aggregated and isolated according to vendors' service requirements. Every logically isolated network partition allocated to a specific customer is called a logically isolated network partition (LINP). A VCDN LINP is an aggregation of virtual resources in all the nodes.
+
+The LINP is managed by LINP management which controls and configures the LINP in terms of VCDN vendors' requirement. The virtual resources and physical resources are managed by resources management. When the requirements of a LINP are changing, the LINP management requires resource management to perform functions such as adding or diminishing the virtual resources to the LINP, moving virtual resources from one node to the other node. When resource management is required to adjust backbone network performance, the resource management requires that network controller performs functions such as optimize routing, expanding bandwidth, etc. Note that the backbone network may support software defined networking (SDN) functions.
+
+## 8 Objectives
+
+Virtual CDN is a paradigm using cloud computing, network virtualization and SDN technology for content delivery for various multimedia services. VCDN provides a scalable and elastic CDN function pool of shareable physical or virtual resources to multiple vendors with self-service provisioning and administration on demand. See [b-ETSI-GS-NFV001].
+
+The following are the advantages of applying VCDN:
+
+- Suitable for providing service to multiple vendors.  
+VCDN provides on-demand CDN resource provisioning, which dynamically provides resources according to VCDN vendors' needs. So it is more suitable for providing service multiple vendors.
+- Rapid and flexible adaptation to the requirement of vendors.  
+VCDN provides rapid provisioning of service to adapt to vendors' demands by dynamically changing its configurations and re-allocating virtual resources.
+- Increased availability and usage efficiency.  
+VCDN increases the availability and efficiency in the usage of resources by assigning resources to vendors from a large pool of virtual resources.
+- Reduced investment of CDN provider.  
+VCDN is capable of expanding or reducing its virtual resources to accommodate heavier or lighter workloads. All the resources located in different areas are shared, instead of the physical resources in a certain area which can only be used by the service distributed in that area. Allocating virtual resources increases capability with lower cost than adding physical resources.
+- Increased resiliency and robustness.  
+VCDN is totally deployed in virtualization of network and computing resources, it can implement service chaining without limitation of physical networks.
+
+## 9 Requirements
+
+This clause addresses the requirements for VCDN.
+
+### 9.1 Service provision requirements
+
+VCDN service provision requirements include basic content delivery service provision requirements and special requirements for implementation of virtual CDN. Basic content delivery service provision
+
+requirements are provided in [ITU-T Y.1901], [ITU-T Y.2019] and [b-ETSI-TS-182019]. The related requirements are detailed in clause 6.6.4.1 "Content delivery" of [ITU-T Y.1901] and clause 8 "Content delivery requirements" of [ITU-T Y.2019].
+
+The special requirements for implementation of virtual CDN are as follows:
+
+- The virtual CDN is required to support providing various multi-vendor services.
+- The virtual CDN is required to support legacy CDN service provision, including content downloading, delivery of multiple audio streams, accelerating web page presenting and so on.
+- The virtual CDN is required to support that multiple virtual resources of multiple VCDN vendors be logically isolated from each other.
+- The virtual CDN optionally provides different priority levels for different VCDN vendors according to their service level agreement (SLA).
+- The virtual CDN is required to support dynamic change of its configuration and re-allocation of virtual resources according to VCDN vendors' requirements.
+
+### **9.2 Physical resource management requirements**
+
+Physical resource management enables the configuration of all physical resources used in the VCDN, such as storage, servers and networks used by different VCDN vendors. The requirements for the physical resource management are as follows:
+
+- The physical resource management is recommended to provide the capabilities of managing, configuring, controlling, and monitoring all physical resources for virtual resource management.
+- The physical resource management is recommended to provide diagnostic mechanisms for trouble-shooting to help identify the causes of physical resources failures.
+- The physical resource management is recommended to provide information obtained through the diagnostic mechanisms (e.g., expected recovery time) to virtual resource management.
+- The physical resource management is recommended to detect new physical resources automatically as they are added to the network.
+- The physical resource management is recommended to provide authentication, authorization, and accounting (AAA) mechanisms.
+
+### **9.3 Virtual resource requirements**
+
+#### **9.3.1 Virtual machine requirements**
+
+Physical servers can be abstracted into virtual machines (VMs) in VCDN. Virtual machines provide service functions of CDN, such as media service, load balance service, statistical service and network management. A virtual machine pool is composed of many single virtual machines, the VCDN LINP can utilize the VM in a virtual machine pool according to the requirements of VCDN vendors. The requirements for the virtual machine are as follows.
+
+- The virtual machine is required to provide a virtualized and isolated computing environment for each operating system (OS).
+- The virtual machine is required to support migration of virtual machines between different physical computing machines.
+- The virtual machine's central processing unit (CPU) is required to support virtualization, which allows running multiple virtual CPUs (vCPU) on a single physical CPU.
+- The virtual machine's vCPUs' computing capability can optionally be specified as a fraction of a physical CPU.
+
+- The virtual machine's memory is required to support virtualization, which allows memory allocation and memory release when the virtual machine activates and shutdowns.
+- The virtual machine is required for the hypervisor to support input/output (I/O) virtualization capabilities.
+- The virtual machine is required to be capable of using virtual I/O devices abstracted from the physical I/O devices.
+- The virtual machine's physical network interface is required to support virtualization, where the physical network interface can be virtualized into multiple virtual network interfaces.
+- The virtual machine's physical network interface is required to support virtualization; different virtual machines can be grouped into one virtual local network.
+- The virtual machine can optionally be duplicated to create a new virtual machine with the same configuration.
+- The virtual machine is recommended to support the static and dynamic migration of a virtual machine.
+
+#### 9.3.2 Virtual storage requirements
+
+Physical storage devices can be converted into virtual storage in VCDN. Virtual storage provides the storage function of CDN, such as storing media files and databases. The VCDN LINP can utilize the virtual storage according to the requirements of VCDN vendors. The requirements for the virtual storage are as follows:
+
+- Virtual storage is recommended to provide the capability for the VCDN application to store content by ignoring the difference of storage resources at the physical level, such as storage network architecture, storage (read/write) protocols, physical storage medium, etc.
+- Virtual storage is recommended to provide the capability for the VCDN to dynamically adjust its virtual storage resources according to application requirements. For example to change its storage space, file migration, etc.
+- Virtual storage is required to provide storage interfaces, such as structured data-sharing access interfaces, block storage interfaces or file system interfaces as well as access data path interfaces.
+- Virtual storage is required to provide the capabilities for user authentication and authorization.
+- Virtual storage is required to provide basic configuration capabilities, including storage domain configuration, file system namespace configuration, storage resources configuration and local file system configuration.
+- Virtual storage is recommended to provide performance monitoring and statistics (e.g., disk I/O speed, disk space usage, CPU utilization, memory utilization, job completion).
+- Virtual storage is recommended to provide storage migration functions. Based on migration policies, data can be migrated between different storage devices, which can be local storage or shared storage.
+- Virtual storage is recommended to provide storage backup functions. Backup can be applied at block level and file level storage.
+
+#### 9.3.3 Virtual CDN network requirements
+
+A virtual CDN network provides network functions in one CDN node. Virtual CDN network functions are the functions of the specified intranet network which is applied to access and interconnect servers in one CDN node, instead of backbone network which is connected to other CDN nodes. A virtual CDN network provides network functions such as IP address allocation, virtual local
+
+area network (VLAN) allocation, and virtual switching, among other functions. The requirements for virtual CDN network are as follows:
+
+- A virtual CDN network is recommended to support the dynamic migration of virtual machines. The related resources of virtual machines can be migrated with virtual machines migration. The service cannot be interrupted during virtual machine migration.
+- A virtual CDN network is recommended to provide elastic addressing for different virtual machines. It is recommended to support public IP address and private IP address mapping.
+- A virtual CDN network is recommended to support the isolation of the logical network among virtual machines, such as establishment of a VLAN network.
+- A virtual CDN network is recommended to support different security policies for particular virtual machines, such as access control list (ACL) and firewalls, etc.
+- A virtual CDN network is recommended to support different quality of service (QoS) and bandwidth policies for different virtual machines.
+- A virtual CDN network is recommended to support traffic monitoring and traffic statistics among virtual machines and network ports.
+
+#### **9.3.4 Software resource provisioning requirements**
+
+The software resources include the software for deploying virtual resource, and the software in support of service implementation. The requirements for the software resource are as follows:
+
+- The software resource provisioning is recommended to provide a functionality to configure all virtual resources to support operations automated provisioning and deployment.
+- The software resource provisioning is recommended to support automated deployment according to the service requirement, which can promote provisioning efficiency.
+- The software resource provisioning is recommended to be easy to be programmed and understood.
+- The software resource management is recommended to be unified, including capabilities for licence information registration, allocation, recovery, expiration notification and metering.
+
+#### **9.3.5 Virtual resource management**
+
+The virtual resources management enables VCDN LINP operators to apply management policies to a VCDN LINP. The requirements for the LINP management are as follows:
+
+- The virtual resource management is recommended to provide physical-to-physical resources mapping and physical-to-virtual resources mapping management.
+- The virtual resource management is recommended to provide the secure isolation in addition to conventional control plane and data plane isolation among LINPs.
+- The virtual resource management is recommended to support topology awareness to allow the virtual resources to effectively interact with each other during the construction of LINPs.
+- The virtual resource management is recommended to adjust the capability of LINPs according to the changes of requirements and the reconfiguration.
+- The virtual resources management is recommended to build cloud infrastructure resource pools, and to support service implementation.
+
+### **9.4 VCDN LINP requirements**
+
+#### **9.4.1 VCDN LINP function requirements**
+
+The VCDN LINP is an aggregation of virtual resources in all the nodes. A VCDN LINP is created by the LINP manager and generated by using virtualized resources. The requirements for the VCDN LINPs are as follows:
+
+- The VCDN LINP is recommended to be created and that it inherits appropriate control rights from the virtual resources manager controlling all virtual resources.
+- The VCDN LINP is recommended to consist of a set of virtual resources that are independently manageable partition of physical resources.
+- The VCDN LINP is recommended to abstract specific physical resources. The vendors can access the capabilities of virtual resources by using abstracted interfaces to deliver content.
+- The VCDN LINP is recommended to be isolated from each other. LINPs may not mutually interfere with each other in terms of performance, security, and namespace. Any single LINP may not cause disruptions to other LINPs or physical networks.
+- The VCDN LINP is recommended to be flexibly allocated, reclaimed and released according to the requirement of VCDN. It can automatically maximize the accommodation of multiple LINPs on physical resources and optimize the usage of the physical resources.
+
+#### **9.4.2 VCDN LINP management requirements**
+
+The VCDN LINP management enables VCDN LINP operators to apply management policies to a VCDN LINP. The requirements for the LINP management are as follows:
+
+- The VCDN LINP management is recommended to align the allocation of virtual and physical resources in a LINP.
+- The VCDN LINP management is recommended to reconfigure a LINP by reallocating virtual resources to the LINP so that the LINP operator can adapt the LINP profile to changes in service properties.
+- The VCDN LINP management is recommended to terminate a LINP and release all the virtual resources that are no longer needed.
+- The VCDN LINP management is recommended to provide independently managing LINP which is isolated from others.
+- The VCDN LINP management is recommended to provide visible management operations such as monitoring, fault detection, topology awareness and reconfiguration, resource discovery/allocation/scheduling and customized control.
+- The VCDN LINP management is recommended to provide abstracting the information of physical resources and supporting the simplified or the higher level interfaces for resource control.
+- The VCDN LINP management is recommended to provide constructing or reconfiguring a LINP.
+- The VCDN LINP management is recommended to optimize a LINP so that the LINP can be controlled and managed efficiently to adapt to all kinds of changes, such as traffic fluctuation and network congestion.
+- The VCDN LINP management is recommended to provide authentication and authorization to achieve safe and secure operations of VCDN LINPs.
+
+### **9.5 Service management requirements**
+
+VCDN service management enables a VCDN provider to support service provisioning to VCDN vendors:
+
+- The virtual CDN is required to support providing a VCDN customer management system. The VCDN provider can add or remove vendors, clarify vendors group, customer's credit management and contract management, etc.
+- The virtual CDN is required to support customer self-service portal. VCDN vendors can manage and operate VCDN service by themselves through customer self-service portal.
+
+- The virtual CDN is required to support authentication, authorization, and accounting (AAA) mechanism. The mechanism is recommended to be executed before a VCDN provider or a VCDN customer entity accesses the management entity.
+- The virtual CDN optionally provides vendors with the possibility to submit VCDN service requirement, such as storage and server capacity, content delivery areas, terminal client condition.
+- The virtual CDN optionally provides vendors with the possibility to manage content, including ingest contents to the LINP, remove contents, updated contents, etc.
+- The virtual CDN optionally provides vendors with the possibility to query VCDN service statistics, such as the usage of storage, number of times that the contents have been downloaded, number of online clients, etc.
+- The virtual CDN optionally provides system statistics. It supports various statistics mode, such as usage of storage, total flow, number of nodes.
+
+## 10 Backbone network requirements
+
+VCDN resource management communicates with the backbone network in accordance with VCDN customer requirements, including traffic changes, node migrations and SLA changes. As opposed to the VCDN network, the backbone network is defined as the network that inter-connects all nodes of the VCDN, instead of the intra network of a specific VCDN node. The backbone network is required to transfer content data from VCDN nodes to end users. The backbone network is required to support the software defined networking (SDN) function. The network controller can adjust performance according to resource management requirements. Resource management requires the network controller to perform functions such as routing optimization and expansion of bandwidth, among others. The requirements for a virtual CDN network are as follows:
+
+- Backbone network is required to provide a functionality to discover the underlying network topology to see how the network devices (e.g., SDN-enabled switches and routers) connect to each other.
+- Backbone network is required to provide functionalities for programmability, abstraction, and the orchestration of the SDN devices.
+- Backbone network is required to provide a functionality to collect network information about the capability of the network devices and network information including status of forwarding tables, routing policies, and network topologies.
+- Backbone network is required to provide a functionality to monitor status (e.g., failure, overload) of network devices.
+- Backbone network is required to provide a connectivity between VCDN nodes. By means of this connectivity, a superior node can interwork with the subordinate VCDN nodes to request contents that the nodes do not have, including transfer of virtual machines between connected nodes.
+- Backbone network is required to provide the service level agreement capability according to the requirement of VCDN vendors. The SLA requirements (including QoS) of a VCDN customer for a given content delivery service are expected to be met by appropriate interworking with selected VCDN nodes, even in the event of service performance degradation or a disaster.
+
+## 11 Security considerations
+
+Since a VCDN consists of virtual resources that are available to multiple vendors, security issues regarding network virtualization can be raised. Every customer can administer their own LINP. LINP has some network virtualization properties, such as flexibility, configurability, network abstraction and so on. So those kind of properties can cause unexpected security and privacy issues.
+
+Therefore, the following security issues should be considered to mitigate potential security problems. Security and privacy issues should be considered during planning and designing network virtualization solutions. The issues can include security and privacy requirements of VCDN vendors, VCDN providers and end users. In order to prevent malicious access, the AAA functions are essential to operate LINPs. In addition, it is necessary to keep monitoring the security and privacy of data and applications that are implemented and deployed in VCDN LINPs.
+
+## Appendix I
+
+### Use cases for VCDN
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The traditional CDN model for distributing content is based on cache servers located at the edge of the network (those closest to the end users) for delivering content to end users in a reliable and timely manner. Generally, the capacity and service function of physical devices are deployed according to the requirement of the users in that area.
+
+There are some disadvantages that come with this model. When service demand is dramatically and tentatively raised in area A, the CDN operator only adds physical cache servers to meet the requirement, while the workload of cache servers in the B area are very low, but they could not be shared with the cache servers in area A. However, when the service demand is decreased in area A, the load of cache servers becomes low. In that case, it comes at a higher operational cost for CDN operators..
+
+Virtual CDN can deal with the issues mentioned above. VCDN uses virtualization technology to virtualize cache servers in any area. VCDN service provider ensures service sustainability and flexibly to manage their networks according to service demands without complexity. Distribution resources are not limited in its own local area of users, if the resource of virtual machine overloads in area A, while the load of virtual machine in area B is low. The central controller gets the message and logically distributes some of area B's virtual machine resources to area A to service users in area A. In addition, the central controller also distributes some network capacity to area A, such as bandwidth or superior QoS.
+
+### I.1 Use case 1: the number of users is rapidly rising in one area
+
+This use case is illustrated in Figure I.1. A VCDN vendor provides a popular service, so the number of users is dramatically rising. However, the storage and distribution resources of the node of that area are insufficient. Hence, VCDN allocates some virtual resources to the node from another node. At the same time, the VCDN informs the SDN enabled network controller to allocate the network resource via the content delivery paths, which can guarantee quality of delivery contents service.
+
+- 1) The number of users is dramatically rising when some new services which are popular are provided to the area.
+- 2) The customer of the VCDN notices this issue and needs more content delivery resources. The VCDN resource management and LINP management find there is no more resources in node 1 which is the best node to provide service in the area.
+- 3) But more resources are unused in node 2. So some virtual resources identified as N2V3 are allocated to provide service to the area.
+- 4) At the same time, SDN enabled network controller is required to provide a better network path for providing delivery content service from node 2 to the users in the area.
+- 5) The network controller allocates a best path to the service according to the topology information to guarantee the quality of service. Users can also receive best service from node 2.
+
+NOTE – The identification in the node ellipse, which is described as NxVx in Figures I.1 and I.2, represents the virtual resources allocated by LINP management. This means that it is located in the specific node and the number of virtual resource. Letter "N" represents the node and letter "V" represents the virtual resource. The numbers after letters "N" and "V" represents the resource number. For example, N2V3 indicates that it belongs to node 2, and that it is the third virtual resource.
+
+![Diagram of Figure I.1 showing network management and user distribution. At the top, three management boxes are connected in a chain: 'Resource management' (2) -> 'LINP management' (4) -> 'Network controller'. Below them are two nodes: 'Node 2' (3) containing virtual nodes N2V1, N2V2, and N2V3; and 'Node 1' containing virtual nodes NIV1, NIV2, NIV3, and NIV4. Both nodes are connected to a central 'Backbone network' (5) which consists of five interconnected switches. Below the backbone network are two groups of 'End users'. A callout bubble (1) next to the right group of users states 'The number of users is rising rapidly'. Green dashed lines connect the nodes to the backbone network, and red dashed lines connect the backbone network to the end users. A small label 'F.743.4(17)_FI.1' is in the bottom right corner.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+Diagram of Figure I.1 showing network management and user distribution. At the top, three management boxes are connected in a chain: 'Resource management' (2) -> 'LINP management' (4) -> 'Network controller'. Below them are two nodes: 'Node 2' (3) containing virtual nodes N2V1, N2V2, and N2V3; and 'Node 1' containing virtual nodes NIV1, NIV2, NIV3, and NIV4. Both nodes are connected to a central 'Backbone network' (5) which consists of five interconnected switches. Below the backbone network are two groups of 'End users'. A callout bubble (1) next to the right group of users states 'The number of users is rising rapidly'. Green dashed lines connect the nodes to the backbone network, and red dashed lines connect the backbone network to the end users. A small label 'F.743.4(17)\_FI.1' is in the bottom right corner.
+
+**Figure I.1 – Use case 1: The number of users is rapidly rising in one area**
+
+### I.2 Use case 2: one node is broken
+
+This use case is illustrated in Figure I.2.
+
+When the hardware, software and network of a certain node fails, this leads to content delivery service disruption. VCDN then allocates the service of the node to another node. At the same time, the VCDN informs the SDN enabled network controller to allocate the network resource via the content delivery paths, which can guarantee quality of delivery contents service.
+
+- 1) Node 1 is broken for some reason.
+- 2) The VCDN resource management and LINP management detect it.
+- 3) Virtual resources identified as N2V3 and N2V4 in node 2 are allocated to provide service taking place node 1.
+- 4) At the same time, SDN enabled network controller is required to provide a better network path for providing delivery content service from node 2 to the users in the area.
+- 5) Network controller allocates a best path to the service according to topology information to guarantee the quality of service. Users can also receive best service from node 2.
+
+![Network diagram showing a broken node (Node 1) and its impact on end users. The diagram includes Resource management, LINP management, Network controller, Node 1, Node 2, a Backbone network, and End users. Node 1 is marked as broken, and its failure is shown affecting the network paths to end users.](9c6461e1e94afae4dec455e69a2ce152_img.jpg)
+
+The diagram illustrates a network architecture with the following components and connections:
+
+- Management Layer:** At the top, three boxes are connected in a chain: **Resource management** (②) — **LINP management** (④) — **Network controller**. Dashed lines connect **Resource management** and **LINP management** to both **Node 1** and **Node 2**. The **Network controller** is connected to **Node 1**.
+- Nodes:**
+  - Node 1** (①) is a cloud containing four sub-components: **N1V1** (yellow), **N1V2** (yellow), **N1V3** (blue), and **N1V4** (blue). A red starburst icon next to it says "The node is broken".
+  - Node 2** (③) is a cloud containing four sub-components: **N2V1** (blue), **N2V2** (yellow), **N2V3** (yellow), and **N2V4** (yellow).
+- Backbone network:** A central cloud (⑤) labeled "Backbone network" contains five router icons. A red dashed line connects a router on the left (receiving input from **Node 2**) to a router on the right (connected to **Node 1**). A green dashed line also connects the left router to the **End users** below **Node 2**.
+- End users:**
+  - Below **Node 2**, an oval labeled "End users" contains icons of two desktop computers and one laptop. It is connected to the left router in the backbone network by a green dashed line.
+  - Below **Node 1**, an oval labeled "End users" contains icons of two desktop computers, one laptop, and one tablet. It is connected to the right router in the backbone network by a green dashed line. A red dashed line with an arrow points from the right router to this group of users, indicating a failed or degraded connection due to the broken node.
+
+Network diagram showing a broken node (Node 1) and its impact on end users. The diagram includes Resource management, LINP management, Network controller, Node 1, Node 2, a Backbone network, and End users. Node 1 is marked as broken, and its failure is shown affecting the network paths to end users.
+
+F.743.4(17)\_FI.2
+
+Figure I.2 – Use case 2: One node is broken
+
+## Bibliography
+
+- [b-ETSI-GS-NFV001] ETSI GS NFW 001 V1.1.1 (2013), *Network Functions Virtualisation (NFV); Use Cases.*  
+<[http://www.etsi.org/deliver/etsi\\_gs/NFV/001\\_099/001/01.01.01\\_60/gs\\_NFV001v010101p.pdf](http://www.etsi.org/deliver/etsi_gs/NFV/001_099/001/01.01.01_60/gs_NFV001v010101p.pdf)>
+- [b-ETSI-TS-182019] ETSI TS 182 019 V.3.12 (2011), *Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Content Delivery Network (CDN) Architecture.*  
+<[http://www.etsi.org/deliver/etsi\\_ts/182000\\_182099/182019/03.01.02\\_60/ts\\_182019v030102p.pdf](http://www.etsi.org/deliver/etsi_ts/182000_182099/182019/03.01.02_60/ts_182019v030102p.pdf)>
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.743.7-201905-I_PDF-E/raw.md

@@ -0,0 +1,391 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.7**
+
+(05/2019)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for big data-enhanced visual  
+surveillance services**
+
+Recommendation ITU-T F.743.7
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a stylized globe with a red lightning bolt striking through it. The letters "ITU" are prominently displayed in blue and red.
+
+ITU logo
+
+International  
+Telecommunication  
+Union
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multidestination satellite services         | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## Recommendation ITU-T F.743.7
+
+## Requirements for big data-enhanced visual surveillance services
+
+## Summary
+
+Recommendation ITU-T F.743.7 specifies requirements for visual surveillance enhanced by big data (VSBD) services. It promotes the value of visual surveillance services by using big data analytics method and tools. Massive video, event and sensing data are analysed to support enhanced visual surveillance services, including video retrieval, event detection and status prediction.
+
+Recommendation ITU-T F.743.7 provides application scenarios, service requirements, functional requirements, performance and security requirements for VSBD services.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.7  | 2019-05-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/13897">11.1002/1000/13897</a> |
+
+## Keywords
+
+Big data, requirement, visual surveillance.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2019
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                               | Page |
+|-----------------------------------------------|------|
+| 1 Scope.....                                  | 1    |
+| 2 References.....                             | 1    |
+| 3 Definitions .....                           | 1    |
+| 3.1 Terms defined elsewhere .....             | 1    |
+| 3.2 Terms defined in this Recommendation..... | 1    |
+| 4 Abbreviations and acronyms .....            | 1    |
+| 5 Conventions .....                           | 1    |
+| 6 Application scenarios.....                  | 2    |
+| 6.1 Intelligent video retrieval .....         | 2    |
+| 6.2 Intelligent event detection .....         | 2    |
+| 6.3 Status prediction .....                   | 2    |
+| 7 Service requirements .....                  | 2    |
+| 7.1 Video retrieval.....                      | 2    |
+| 7.2 Statistical analytics .....               | 3    |
+| 7.3 Behaviour analytics .....                 | 3    |
+| 7.4 Status prediction .....                   | 3    |
+| 7.5 Event analytics.....                      | 3    |
+| 7.6 Data mining and analytics .....           | 3    |
+| 7.7 Import of special analytics model.....    | 4    |
+| 7.8 Visual display .....                      | 4    |
+| 8 Functional requirements .....               | 4    |
+| 8.1 Data collection requirement .....         | 4    |
+| 8.2 Data-processing requirement.....          | 4    |
+| 8.3 Data storage requirement.....             | 5    |
+| 9 Performance requirements .....              | 5    |
+| 10 Security requirements .....                | 5    |
+| Bibliography.....                             | 6    |
+
+
+
+## Recommendation ITU-T F.743.7
+
+## Requirements for big data-enhanced visual surveillance services
+
+# 1 Scope
+
+This Recommendation specifies requirements for big data-enhanced visual surveillance service.
+
+The scope of this Recommendation includes:
+
+- application scenarios;
+- service requirements;
+- functional requirements;
+- performance requirements;
+- security requirements.
+
+# 2 References
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 visual surveillance** [b-ITU-T F.743]: A telecommunication service focusing on video (but including audio) application technology, which is used to remotely capture multimedia (such as audio, video, image, alarm signals, etc.) and present them to the end user in a friendly manner, based on a managed broadband network with quality, security and reliability ensured.
+
+## 3.2 Terms defined in this Recommendation
+
+None.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+ETL Extract-Transform-Load
+
+ML Machine Learning
+
+PTZ Pan/Tilt Zoom
+
+VSBD Visual Surveillance enhanced by Big Data
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement needs not be present to claim conformance.
+
+The keywords "can optionally" and "may" indicate an optional requirement which is permissible, without implying any sense of being recommended. These terms are not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+# **6 Application scenarios**
+
+## **6.1 Intelligent video retrieval**
+
+It is difficult for traditional video surveillance to retrieve a specific object in massive video data. However, a user can use text, picture or video as input to search in a large number of videos according to the various characteristics of the objects in visual surveillance enhanced by big data (VSBD). Two examples follow.
+
+- a. Using the image of the target person as input, users can quickly search for similar objects in massive videos according to the facial, clothing colour distribution or body features of the image.
+- b. Using characteristic information such as licence plate, vehicle type, colour, brand type or body feature of the target vehicle as input, users can retrieve similar objects in multiple videos with the trajectories displayed.
+
+## **6.2 Intelligent event detection**
+
+VSBD can automatically identify specific events (fire, fake licence plate, etc.) that users are interested in based on various data. The data can be derived from multiple video sources or video and sensor data combinations. The criteria for identifying specific events can be predefined rules or models learned from machine learning (ML).
+
+For example, VSBD can detect a fire disaster by analysing the related real-time videos as well as sensing data from smoke detectors and temperature sensors in areas of concern to users.
+
+## **6.3 Status prediction**
+
+The value of traditional video surveillance data has not been explored. VSBD can effectively exploit the value of historical data. It can extract a large amount of effective information from video surveillance data and be used in many aspects of prediction. For example, according to the data collected by cameras, VSBD can analyse the rules and forecast future traffic flow in order to achieve efficient traffic control.
+
+# **7 Service requirements**
+
+## **7.1 Video retrieval**
+
+### **7.1.1 Object retrieval**
+
+SRV001: VSBD is required to support various conditional retrieval inputs and search objects in massive video data across cameras by different abstract features rapidly.
+
+SRV002: VSBD is required to support continuous video capture for selected objects.
+
+SRV003: VSBD is required to adapt automatically despite scenarios, illumination, camera angles and position.
+
+### **7.1.2 Event retrieval**
+
+SRV004: VSBD is required to support retrieval of the characteristics for particular events, such as people gathering in time and space. A VSDB is required to support the statistics for the selected range of alarm events.
+
+### **7.1.3 Integrated retrieval**
+
+SRV005: VSBD is recommended to support real-time and historical trajectories video retrieval from real-time video and historical database by the conditions of time, space, hot events, features marks and object people or vehicles.
+
+## **7.2 Statistical analytics**
+
+SRV006: VSBD is required to support data collection for vehicle classification, trajectory tracking and monitoring, and registration location.
+
+SRV007: VSBD is required to support data collection of the flow of vehicle or people in certain locations or time periods, and output the alarm information according to the results from big data analytics.
+
+SRV008: VSBD is required to support using big data-processing capabilities to identify suspected fake plate vehicles from the massive licence plate data captured every day.
+
+SRV009: VSBD is required to support identification of trailing vehicles from video data features.
+
+## **7.3 Behaviour analytics**
+
+SRV010: VSBD is required to support people behaviour analytics, such as trajectory reappearance and frequent entry and exit.
+
+SRV011: VSBD is required to support vehicle behaviour analytics, such as fake plate vehicle scanning, first time appearance within the specified range, one vehicle multiple plates, similar licence plate differentiation, frequent overtaking, trajectory reappearance, vehicles travelling together and user-defined collision.
+
+## **7.4 Status prediction**
+
+SRV012: VSBD is required to support the display of different kinds of status predictions, such as the incidence of certain types of criminal case trend prediction, for decision aids through statistical analytics from huge network-wide data.
+
+## **7.5 Event analytics**
+
+SRV013: VSBD is required to find valuable clues from massive historical cases.
+
+SRV014: VSBD is required to support analytics of specific events from a large number of video data and alarm information.
+
+## **7.6 Data mining and analytics**
+
+SRV015: VSBD is required to support the retrieval of system metadata, data mining and analytics function.
+
+SRV016: VSBD is required to support integration of non-video data, mine events correlation and production mode, so as to increase the value of video data.
+
+## **7.7 Import of special analytics model**
+
+SRV017: VSBD is required to support import of the special analytics model that is to computerize, streamline and populate the analytics thinking method and process from the expert manual work and provide a unified interface to system users.
+
+SRV018: VSBD is required to provide methods for analytics to system users to increase the application value of the video surveillance system through encapsulation of the analytics model.
+
+## **7.8 Visual display**
+
+SRV019: VSBD is required to display highly efficient retrieval comparison results.
+
+SRV020: VSBD is required to improve the practicability of the video data by integrated display with a third-party platform, such as the intelligence analytics platform and the emergency processing platform.
+
+# **8 Functional requirements**
+
+## **8.1 Data collection requirement**
+
+### **8.1.1 Real-time data**
+
+FUN001: VSBD is required to support collection of real-time audio and video data from premises units.
+
+FUN002: VSBD is required to support collection of real-time data of pan/tilt zoom (PTZ) control messages.
+
+### **8.1.2 Non-real-time data**
+
+FUN003: VSBD is required to support analysis of events (intrusion, stranded, etc.) and use of the resulting information.
+
+FUN004: VSBD is required to support collection of alarming information.
+
+FUN005: VSBD is recommended to support acquisition and analysis of historical case information databases.
+
+FUN006: VSBD is recommended to support acquisition and use of characteristic image databases (crime picture, etc.).
+
+FUN007: VSBD can optionally support use of digital map information databases.
+
+FUN008: VSBD can optionally support using traffic signal databases.
+
+## **8.2 Data-processing requirement**
+
+Based on computer image-processing technology and image recognition algorithm, a visual surveillance system based on big data application can have the capability to understand and analyse the content of videos or images, generate description information from the content in a structured or semi-structured description language, and provide the basis for video big data analytics and application.
+
+### **8.2.1 Image processing and recognition requirement**
+
+FUN009: VSBD is required to extract key frames from videos and restructure the synthesis of new videos.
+
+FUN010: VSBD is recommended to automatically monitor moving objects in videos, extract object trajectories, and combine them into concentrated videos optimally.
+
+FUN011: VSBD is recommended to unify the format and structures of object information in the video in a timely fashion, and extract important information from objects in the video as the meta-data to save, such as colour, people/car classification and perimeter prevention rules.
+
+### **8.2.2 Parallel computing or distributed processing requirement**
+
+FUN012: VSBD is required to support parallel computing or distributed processing technology, so as to provide real-time batch processing and extract-transform-load (ETL) operations.
+
+## **8.3 Data storage requirement**
+
+FUN013: VSBD is required to support persistent storage and operations for massive data.
+
+FUN014: VSBD is required to support storage of various types of structured data, including image index information, vehicle characteristics, human characteristic information, facial feature information and all kinds of characteristic information for the subject research-analytics.
+
+FUN015: VSBD is required to support the storage of a feature-related object image or video in order to assist display and analytics in characteristic information retrieval processes.
+
+FUN016: VSBD is recommended to support localized storage with external or auxiliary data sources.
+
+# **9 Performance requirements**
+
+PRF001: VSBD is required to support object detection index: minimum detectable object size, detection rate, miss rate, error recognition rate and recognition speed.
+
+PRF002: VSBD is required to support analytical prediction: prediction accuracy, mistaken correlated event rate.
+
+PRF003: VSBD is required to support intelligent analytics of high-throughput real-time video. The average processing and response time is recommended to be less than 1 s.
+
+PRF004: VSBD is required to support parallel analytics of single videos by loading multiple algorithms.
+
+# **10 Security requirements**
+
+SEC001: VSBD is required to support security of the video data itself, including data confidentiality, data integrity and authentication.
+
+SEC002: VSBD is required to support security of data protection including the data security during storage and transmission processes.
+
+# Bibliography
+
+- [b-ITU-T F.743] Recommendation ITU-T F.743 (2009), *Requirements and service description for visual surveillance*.
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+International Telecommunication Union
+
+# **ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# **F.743.8**
+
+(05/2019)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for a cloud computing platform  
+supporting a visual surveillance system**
+
+Recommendation ITU-T F.743.8
+
+**ITU-T**
+
+![ITU logo: A globe with a red lightning bolt and the text 'ITU International Telecommunication Union'.](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a stylized globe with a red lightning bolt striking across it. To the right of the globe, the text "ITU" is written in a bold, blue font, and below it, "International Telecommunication Union" is written in a smaller, blue font.
+
+ITU logo: A globe with a red lightning bolt and the text 'ITU International Telecommunication Union'.
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.743.8
+
+# Requirements for a cloud computing platform supporting a visual surveillance system
+
+## Summary
+
+Recommendation ITU-T F.743.8 specifies the requirements for a cloud computing platform supporting visual surveillance. Cloud computing is an emerging technology aimed at providing various computing services over the Internet. Using virtualization technology, a cloud computing platform realizes a ubiquitous and flexible shared resources pool that can be rapidly provisioned and released with minimal management effort or service-provider interaction based on the needs of users. By using the cloud computing technology, the visual surveillance system can conveniently manage various functional components and services, such as video distribution, video transcoding and intelligent video processing. This Recommendation provides the application scenarios and requirements for a cloud computing platform supporting a visual surveillance system.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.8  | 2019-05-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/13898">11.1002/1000/13898</a> |
+
+## Keywords
+
+Cloud computing, requirements, scenarios, visual surveillance.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2019
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                 | Page |
+|---------------------------------------------------------------------------------|------|
+| 1 Scope.....                                                                    | 1    |
+| 2 References.....                                                               | 1    |
+| 3 Definitions .....                                                             | 1    |
+| 3.1 Terms defined elsewhere .....                                               | 1    |
+| 3.2 Terms defined in this Recommendation.....                                   | 1    |
+| 4 Abbreviations and acronyms .....                                              | 1    |
+| 5 Conventions .....                                                             | 2    |
+| 6 Scenarios.....                                                                | 2    |
+| 6.1 Video distribution.....                                                     | 2    |
+| 6.2 Video transcoding.....                                                      | 2    |
+| 6.3 Online intelligent video processing.....                                    | 3    |
+| 6.4 Offline intelligent video processing .....                                  | 4    |
+| 7 Requirements for cloud computing platform supporting visual surveillance..... | 5    |
+| 7.1 User requirements.....                                                      | 5    |
+| 7.2 Service requirements .....                                                  | 5    |
+| 7.3 Security requirements .....                                                 | 6    |
+| 7.4 Management requirements .....                                               | 7    |
+| 7.5 Scalability requirements .....                                              | 7    |
+| 7.6 Reliability requirements .....                                              | 8    |
+| 7.7 Performance requirements.....                                               | 8    |
+| Bibliography.....                                                               | 9    |
+
+
+
+# Recommendation ITU-T F.743.8
+
+## Requirements for a cloud computing platform supporting a visual surveillance system
+
+# 1 Scope
+
+This Recommendation specifies the application scenarios and requirements for a cloud computing platform supporting a visual surveillance system.
+
+# 2 References
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 application** [b-ITU-T Y.101]: A structured set of capabilities, which provide value-added functionality supported by one or more services.
+
+**3.1.2 cloud computing** [b-ITU-T Y.3500]: Paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand.
+
+NOTE – Examples of resources include servers, operating systems, networks, software, applications and storage equipment.
+
+**3.1.3 customer** [b-ITU-T M.60]: An entity which receives services offered by a service provider based on a contractual relationship. It may include the role of a network user.
+
+**3.1.4 customer unit** [b-ITU-T H.626]: A device located at the customer part of a visual surveillance system and used to present multimedia information (such as audio, video, image, alarm signal, etc.) to the end user.
+
+**3.1.5 mobile customer unit (M\_CU)** [b-ITU-T H.626.1]: Mobile client software installed in a customer's mobile devices. The M\_CU is used to initiate the service and provide customers with video viewing.
+
+**3.1.6 premises unit** [b-ITU-T H.626]: A device located at the remote part of a visual surveillance system and used to capture multimedia information (such as audio, video, image, alarm signal, etc.) from a surveilled object.
+
+**3.1.7 visual surveillance** [b-ITU-T H.626]: A telecommunication service focusing on video (but including audio) application technology, which is used to remotely capture multimedia (such as audio, video, image, alarm signals, etc.) and present them to the end user in a user-friendly manner, based on a managed broadband network with ensured quality, security and reliability.
+
+## 3.2 Terms defined in this Recommendation
+
+None.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+CU Customer Unit
+
+|      |                                     |
+|------|-------------------------------------|
+| IVS  | Intelligent Visual Surveillance     |
+| MCU  | Mobile Customer Unit                |
+| MSU  | Media Storage Unit                  |
+| PU   | Premises Unit                       |
+| VS   | Visual Surveillance                 |
+| VSCC | Visual Surveillance Cloud Computing |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+# 6 Scenarios
+
+This clause describes typical scenarios illustrating the cloud computing platform supporting visual surveillance and deriving its service requirements.
+
+## 6.1 Video distribution
+
+The cloud computing platform in a visual surveillance (VS) system can support large-scale real-time video forwarding. For example, many surveillance cameras are deployed in the Great Wall Scenic Area, and the remote monitoring function of the cameras is open to the public. If users wants to see current images of the Great Wall remotely, they can view the network video information on their local devices through the cloud-based real-time video distribution function.
+
+Step 1: Users enter the customer unit (CU) which supports remote live video viewing of the Great Wall Scenic Area, and submit their request to the VS system.
+
+Step 2: After receiving a video-viewing request, the VS system authenticates the user information, and obtains the related information from a video-forwarding function unit that is deployed on the cloud computing platform. The cloud computing platform can dynamically create or destroy the video-forwarding function according to current user requests. The VS system then responds to the CU with the information about the video-forwarding function on the cloud computing platform.
+
+Step 3: After receiving the VS system response, the CU sends a video-viewing request to the cloud computing platform.
+
+Step 4: The cloud computing platform obtains the video stream from the corresponding camera, and then forwards the video stream to the CU.
+
+## 6.2 Video transcoding
+
+The cloud computing platform in a VS system can support video-transcoding functions, e.g., code rate transformation and video format conversion. The traffic department of a city has deployed a large-scale VS system in the city streets with high-definition network cameras. Users want to view the current traffic situation on their way home with their mobile phones. Due to the limited bandwidth of mobile devices and mobile data traffic limits, high-definition surveillance video needs to be transcoded to low-resolution video before forwarding to the CU. The video-transcoding operation can be carried out on the cloud computing platform.
+
+Step 1: Users log into the VS system via their mobile customer unit (MCU), and select the appropriate network camera. The MCU then sends a video-viewing request to the VS system with the video format description.
+
+Step 2: After receiving the video-viewing request, the VS system authenticates the user information, and obtains the related information from a video-forwarding function unit that is deployed on the cloud computing platform. The VS system then responds to the MCU with the information from the video-forwarding function in the cloud computing platform.
+
+Step 3: After receiving the response of the VS system, the MCU sends a video-viewing request to the cloud computing platform.
+
+Step 4: The cloud computing platform obtains the video stream from the corresponding camera. Then, according to the video format description of the MCU, the surveillance video stream is transcoded by the video-transcoding component deployed in the cloud computing platform. The cloud computing platform can dynamically create and destroy the video-forwarding function according to the current requests of the MCU. After that, the transcoded video stream is sent to the MCU.
+
+## **6.3 Online intelligent video processing**
+
+### **6.3.1 Case 1: Traffic flow analysis**
+
+The traffic department of a city has deployed an intelligent visual surveillance (IVS) system for city roads. The system administrator is responsible for operating the IVS system to carry out traffic management tasks. The work of the administrator is to monitor real-time traffic flow of key road sections in the traffic rush hour. A traffic flow analysis function can be developed based on computer vision technology, and is virtualized as functional components in the cloud computing platform. When a user needs to obtain the traffic flow situation of certain road sections, the system can call the traffic flow analysis function to process the relevant surveillance video streams.
+
+Step 1: Users log into the IVS system through the CU. They choose certain surveillance cameras that are deployed on key road sections of interest and set the traffic flow analysis function. They then submit traffic flow analysis requests to the IVS system.
+
+Step 2: After receiving the traffic flow analysis request, the IVS system authenticates the user information, and obtains the relevant information from the traffic flow analysis function that is deployed on the cloud computing platform. The cloud computing platform can dynamically create and destroy the traffic flow analysis function components according to current user requests. The IVS system then responds to the CU with the information from the traffic flow analysis function.
+
+Step 3: After receiving the response of the IVS system, the CU sends the request to the cloud computing platform.
+
+Step 4: The cloud computing platform obtains the relevant video streams from the corresponding cameras, online processes the video streams and then sends the real-time traffic flow analysis results back to the CU.
+
+### **6.3.2 Case 2: Perimeter prevention**
+
+An electricity company uses an IVS system to monitor key power transmission equipment deployed in a city. Surveillance cameras are deployed around the power transmission equipment and the IVS system online analyses the captured surveillance video by calling the perimeter prevention function. Once someone approaches the power transmission equipment, the IVS system generates an alarm message to alert the user to the exception. The perimeter prevention function is virtualized as functional components in the cloud computing platform, and can be dynamically created and destroyed according to current user requests. The working step of the online perimeter prevention scenario is similar to that of the online traffic flow analysis scenario.
+
+## 6.4 Offline intelligent video processing
+
+### 6.4.1 Case 1: Human recognition
+
+A public security department has deployed an IVS system in a city street. The system administrator is responsible for operating the IVS system to carry out public security tasks. When there is a robbery in front of a bank, the administrator reviews the relevant surveillance video captured by the cameras deployed around the bank and obtains a picture of the robber. To find the escape route of the robber as soon as possible, the administrator uses the intelligent human recognition function of the IVS system to process the massive related historical surveillance video. The intelligent human recognition function can be virtualized as functional components in the cloud computing platform and can be dynamically created according to user demand.
+
+Step 1: Users log into the IVS system through the CU. To quickly find robber information in the massive surveillance video data, the user needs to set several functional parameters, such as the camera channel numbers, the time period of interest in the historical video and the picture of the robber, and then sends an intelligent human recognition request to the IVS system.
+
+Step 2: After receiving the human recognition request, the IVS system authenticates the user information, requests the cloud computing platform to create the intelligent human recognition function, and then responds to the CU with the information from the intelligent human recognition function.
+
+Step 3: After receiving the response of the IVS system, the CU sends the request to the cloud computing platform.
+
+Step 4: The cloud computing platform downloads the relevant video files from the media storage unit (MSU), processes the video files in parallel and then sends the human recognition results back to the CU.
+
+Step 5: When the intelligent human recognition task finishes, the cloud computing platform destroys the intelligent human recognition function to release the corresponding resources.
+
+### 6.4.2 Case 2: Video synopsis
+
+The IVS system deployed by a public security department produces massive surveillance video continuously and the cost of data storage is high. However, the public security department is usually interested in moving objects in the surveillance video. Therefore, to save storage space, surveillance video is usually processed to generate synopsis video before long-term storage. The objective of video synopsis is to shorten the video time by reorganizing moving video objects in temporal and spatial dimensions. For example, by using the video synopsis operation, a 24 h surveillance video file is transformed into a 30 min video file that contains all moving objects in the original video file. The intelligent video synopsis function can be virtualized as functional components in the cloud computing platform, and can be dynamically created according to user demand.
+
+Step 1: Users log into the IVS system through the CU, and set several functional parameters of the video synopsis, such as the camera channel numbers, the time period of interest in the historical video and the density of the objects. Then users send an intelligent video synopsis request to the IVS system.
+
+Step 2: After receiving the video synopsis request, the IVS system authenticates the user information, requests the cloud computing platform to create the intelligent video synopsis function and then responds to the CU with the information from the intelligent video synopsis function.
+
+Step 3: After receiving the response of the IVS system, the CU sends the request to the cloud computing platform.
+
+Step 4: The cloud computing platform downloads the relevant video files from the MSU, processes the video files in parallel and then uploads the video synopsis results back to the MSU.
+
+Step 5: When the intelligent video synopsis task finishes, the cloud computing platform destroys the intelligent video synopsis function to release the corresponding resources.
+
+# **7 Requirements for cloud computing platform supporting visual surveillance**
+
+## **7.1 User requirements**
+
+There are two types of user: cloud computing service consumers and cloud computing service providers.
+
+### **7.1.1 Cloud computing service consumer requirements**
+
+- USR-01: A visual surveillance cloud computing (VSCC) platform is required to support registration and de-registration of the end user through the interface provided by the system and the end user can view and modify personal information.
+- USR-02: A VSCC platform is required to support convenient end-user login to and logout from the system. A username and password are required when an end user logs into the system.
+- USR-03: A VSCC platform is recommended to support end-user view of the user access logs or other system logs.
+- USR-04: A VSCC platform is recommended to support real-time surveillance video distribution.
+- USR-05: A VSCC platform is recommended to support the online or offline surveillance video-transcoding function.
+- USR-06: A VSCC platform is recommended to support online or offline intelligent surveillance video analysis functions.
+- USR-07: A VSCC platform is required to support the configuration of computing resources for video surveillance tasks on demand.
+- USR-08: A VSCC platform is required to support the user view of the status of user computing tasks and computing resources.
+
+### **7.1.2 Cloud computing service provider requirements**
+
+- USR-09: A VSCC platform is required to support convenient provider login to and logout from the system. The provider name and password are required when logging into the system.
+- USR-10: A VSCC platform is required to support the provider view of the system operating status from the beginning to now, including the system computing resource occupancy rate, the remaining computing resources of the system, the computing resource occupancy rate of individual users and the remaining computing resources of individual users.
+- USR-11: A VSCC platform is required to support flexible computing resource assignment for individual users.
+
+## **7.2 Service requirements**
+
+### **7.2.1 Online intelligent video processing service requirements**
+
+- SER-01: A VSCC platform is recommended to support online intelligent video processing. The video processing components deployed on a VSCC platform can receive video streams from premises units (PUs) and process the video in real time.
+- SER-02: A VSCC platform is recommended to support online management of video processing tasks, such as creation, pause, restart and deletion.
+- SER-03: A VSCC platform is recommended to view the progress of online video processing tasks.
+
+- SER-04: A VSCC platform is recommended to view the status of resources utilized by online intelligent video processing tasks.
+- SER-05: A VSCC platform is recommended to support the viewing of log files that record the operations of online intelligent video processing tasks.
+
+### **7.2.2 Offline intelligent video processing service requirements**
+
+- SER-06: A VSCC platform is recommended to support offline intelligent video processing. The video processing components deployed on the VSCC platform can download the video files from the MSU and carry out their batch processing.
+- SER-07: A VSCC platform is recommended to support offline management of video processing tasks, such as creation, pause, restart and deletion.
+- SER-08: A VSCC platform is recommended to view the progress of offline video processing tasks.
+- SER-09: A VSCC platform is recommended to view the status of resources utilized by offline intelligent video processing tasks.
+- SER-10: A VSCC platform is recommended to support the viewing of log files that record the operations of offline intelligent video processing tasks.
+
+### **7.2.3 Video transcoding**
+
+- SER-11: A VSCC platform is recommended to support video transcoding. The video-transcoding components deployed on the VSCC platform can receive video streams from PUs and transcode the video in real time. In addition, the video-transcoding components can download video files from the MSU and carry out their transcoding in batches.
+- SER-12: A VSCC platform is recommended to support the management of video-transcoding tasks, e.g., creation, pause, restart and deletion.
+- SER-13: A VSCC platform is recommended to view the progress of video-transcoding tasks.
+- SER-14: A VSCC platform is recommended to view the status of resources utilized by video-transcoding tasks.
+- SER-15: A VSCC platform is recommended to support the viewing of log files that record the operations of video-transcoding tasks.
+
+## **7.3 Security requirements**
+
+### **7.3.1 Authentication security requirements**
+
+- SEC-01: A VSCC platform is required to provide the mechanisms for authentication and authorization, and to permit only authorized users to access the system and use system services. A VSCC platform is required to forbid unauthorized users to handle any system resources.
+
+### **7.3.2 Access security requirements**
+
+- SEC-02: A VSCC platform is required to operate in an environment where network address translation (NAT) or firewall devices are present. It is recommended to utilize specified firewalls, gatekeepers and other network devices to ensure security for access to some special cloud computing services.
+
+### **7.3.3 Content security requirements**
+
+- SEC-03: A VSCC platform is recommended to ensure the security of processed video data, the results of the video processing, etc.
+- SEC-04: A VSCC platform is required to protect user privacy.
+
+### **7.3.4 System security requirements**
+
+- SEC-05: A VSCC platform is required to have the capability to resist various attacks.
+- SEC-06: A VSCC platform is required to provide troubleshooting mechanisms. It is required that a structural single-node problem be avoided (i.e., a problem at a single node should not cause failure of the entire system).
+
+## **7.4 Management requirements**
+
+### **7.4.1 Resources management requirements**
+
+- MAN-01: A VSCC platform is required to support resource management of the cloud computing platform. Resources can be increased and decreased flexibly according to service requests.
+
+### **7.4.2 Equipment management requirements**
+
+- MAN-02: A VSCC platform is required to provide unified management of the computing equipment.
+
+### **7.4.3 Service management requirements**
+
+- MAN-03: A VSCC platform is required to provide various computing service subscription means for users, and to provide the capabilities to query, view and modify their subscription information.
+- MAN-04: A VSCC platform is recommended to provide the capability of accounting, charging and billing for the computing service operation.
+- MAN-05: A VSCC platform is recommended to provide various alternative accounting modes, and to support flexible combination of payment modes, billing modes, billing cycles, preferential pricing, etc.
+
+### **7.4.4 System management requirements**
+
+- MAN-06: A VSCC platform is required to provide a unified system management interface that can be called conveniently.
+- MAN-07: A VSCC platform is required to provide a visual interface for users.
+
+### **7.4.5 Operation management requirements**
+
+- MAN-08: A VSCC platform is required to monitor, record and display the running status of the system.
+- MAN-09: A VSCC platform is required to monitor, record and display usage of cloud computing cluster resources.
+
+## **7.5 Scalability requirements**
+
+- SCA-01: A VSCC platform is required to provide computing resource scalability. When computing equipment is increased or decreased in the system, the computing capacity of the VSCC platform is increased or decreased accordingly, and the system service is uninterrupted.
+- SCA-02: A VSCC platform is required to provide computing resources scalability for users. The computing resources of individual users can be increased or decreased according to each user's demand.
+- SCA-03: A VSCC platform is required to provide user scalability. The number of supported users can be increased or decreased dynamically.
+
+## **7.6 Reliability requirements**
+
+- REL-01: A VSCC platform is required to ensure service reliability. When computing equipment fails or the system network operation is abnormal, the system service can be used normally.
+
+## **7.7 Performance requirements**
+
+- PER-01: A VSCC platform is required to support concurrent user operations. The system can serve a large number of users simultaneously, while ensuring service quality.
+
+## Bibliography
+
+- [b-ITU-T H.626] Recommendation ITU-T H.626 (2011), *Architectural requirements for visual surveillance*.
+- [b-ITU-T H.626.1] Recommendation ITU-T H.626.1 (2013), *Architecture for mobile visual surveillance*.
+- [b-ITU-T M.60] Recommendation ITU-T M.60 (1993), *Maintenance terminology and definitions*.
+- [b-ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014), *Information technology – Cloud computing – Overview and vocabulary*.
+- [b-ITU-T Y.101] Recommendation ITU-T Y.101 (2000), *Global Information Infrastructure terminology: Terms and definitions*.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.743.9**
+
+(05/2019)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Use cases and requirements for a multimedia  
+content delivery network**
+
+Recommendation ITU-T F.743.9
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a stylized globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in a blue, sans-serif font, with "ITU" in a larger, bold font above it.
+
+ITU logo
+
+International  
+Telecommunication  
+Union
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.743.9
+
+# Use cases and requirements for a multimedia content delivery network
+
+## Summary
+
+Recommendation ITU-T F.743.9 illustrates a content delivery network (CDN), and defines use cases for a multimedia CDN in two categories: content delivery and capability, as well as the requirements for a CDN.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.743.9  | 2019-05-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/13899">11.1002/1000/13899</a> |
+
+## Keywords
+
+Multimedia content delivery network, requirement, use case.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2019
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                               | Page |
+|-----------------------------------------------|------|
+| 1 Scope.....                                  | 1    |
+| 2 References.....                             | 1    |
+| 3 Definitions .....                           | 1    |
+| 3.1 Terms defined elsewhere .....             | 1    |
+| 3.2 Terms defined in this Recommendation..... | 1    |
+| 4 Abbreviations and acronyms .....            | 1    |
+| 5 Convention.....                             | 2    |
+| 6 Background.....                             | 2    |
+| 7 Use cases.....                              | 3    |
+| 7.1 Content delivery use cases.....           | 3    |
+| 7.2 Capability use cases.....                 | 5    |
+| 8 Requirements .....                          | 5    |
+| 8.1 General requirements.....                 | 5    |
+| 8.2 Service-oriented requirements .....       | 6    |
+| 8.3 Requirement for security .....            | 6    |
+| Bibliography.....                             | 8    |
+
+
+
+# Recommendation ITU-T F.743.9
+
+## Use cases and requirements for a multimedia content delivery network
+
+## 1 Scope
+
+This Recommendation specifies a content delivery network (CDN), and describes use cases for multimedia CDN in two categories: content delivery and capability use cases, as well as the requirements for multimedia CDN.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T F.743.5] Recommendation ITU-T F.743.5 (2018), *Framework and interfaces for multimedia content delivery network*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 content** [ITU-T H.780]: A combination of audio, still image, graphic, video, or data.
+
+**3.1.2 content delivery network** [b-ITU-T Y.2084]: A content delivery network (CDN) is a system of distributed servers that deliver content (e.g., web pages, files, videos and audios) to users based on pre-defined criteria such as the geographic locations of users, the status of the content delivery server and the IP network connection.
+
+**3.1.3 dynamic content** [ITU-T F.743.5]: Contents created on demand while a user dynamically operates a web application.
+
+**3.1.4 static content** [ITU-T F.743.5]: Content that changes infrequently. This type of content is not changed with the requests of users.
+
+## 3.2 Terms defined in this Recommendation
+
+None.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                          |
+|-----|--------------------------|
+| CDN | Content Delivery Network |
+| IP  | Internet Protocol        |
+| QoE | Quality of Experience    |
+| QoS | Quality of Service       |
+
+# 5 Convention
+
+In this Recommendation:
+
+The keywords 'is required to' indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords 'is prohibited from' indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords 'is recommended' indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+The keywords 'is not recommended' indicate a requirement which is not recommended but which is not specifically prohibited. Thus, conformance with this specification can still be claimed even if this requirement is present.
+
+The keywords 'can optionally' indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Background
+
+Nowadays, the Internet has become an important network infrastructure for delivering content. Because of the best effort nature of the Internet, quality of service (QoS) and quality of experience (QoE) provided by content services are not able to meet consumers' content quality expectations, which is aggravated by the rapid growth of the number of Internet users and Internet content providers. Both content consumers and content providers seek content service QoS and QoE improvements. Meanwhile, traffic related to content services will meet its bandwidth bottleneck of backbone networks and investment in information technology infrastructure by content providers will become greater and greater. Therefore, CDN technology is the most appropriate solution for wide adoption in the current market.
+
+Typically, a CDN consists of functions for content distribution and control, content delivery, content routing and redirection and management. For the high-level framework of multimedia CDN, see clause 8.2 of [ITU-T F.743.5].
+
+A networking sketch of a CDN is shown in Figure 6-1.
+
+![Diagram illustrating a content delivery network (CDN) architecture. A central 'CDN' oval contains 'Content routing', 'Storage and distribution', 'Edge server 1', 'Edge server n', and 'Usage record'. External components include 'Resource server', 'Billing system', 'User 1', and 'User n'. Arrows show data flow: Resource server to Storage and distribution; Storage and distribution to Edge servers; Content routing to Edge servers; Edge servers to Usage record; Usage record to Billing system and Resource server; User 1 and User n to Edge servers.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+```
+
+graph TD
+    subgraph CDN
+        CR[Content routing]
+        SD[Storage and distribution]
+        ES1[Edge server 1]
+        ESn[Edge server n]
+        UR[Usage record]
+    end
+    RS[Resource server]
+    BS[Billing system]
+    U1[User 1]
+    Un[User n]
+
+    RS --> SD
+    SD --> ES1
+    SD --> ESn
+    CR --> ES1
+    CR --> ESn
+    ES1 --> UR
+    ESn --> UR
+    UR --> BS
+    UR --> RS
+    U1 --> ES1
+    Un --> ESn
+  
+```
+
+F.743.9(19)\_F6-1
+
+Diagram illustrating a content delivery network (CDN) architecture. A central 'CDN' oval contains 'Content routing', 'Storage and distribution', 'Edge server 1', 'Edge server n', and 'Usage record'. External components include 'Resource server', 'Billing system', 'User 1', and 'User n'. Arrows show data flow: Resource server to Storage and distribution; Storage and distribution to Edge servers; Content routing to Edge servers; Edge servers to Usage record; Usage record to Billing system and Resource server; User 1 and User n to Edge servers.
+
+**Figure 6-1 – Illustration of content delivery network**
+
+Basically, the original content provided by a content provider on the resource server should be ingested into the storage and distribution system first and then be pushed to the edge servers, according to the CDN operator strategy. While an end-user requests specific content, that request would be redirected by the content routing server to a CDN edge server that is close to that end-user and is able to provide a content consumption service. When the content is consumed on the edge server, content usage information will be collected by the usage record server and then transferred to both the billing system handled by the CDN operator and the resource server handled by the content provider.
+
+A CDN can provide services for a single or several content providers. The types of content delivered by a CDN may be static content, dynamic content or a mixture of the two, based on requirements.
+
+## 7 Use cases
+
+## 7.1 Content delivery use cases
+
+#### 7.1.1 Static content delivery
+
+##### 7.1.1.1 Static web page browsing, file downloading and audio/video on demand
+
+In these use cases, a CDN distributes static content from the original server to its edge nodes based on the distribution policy between the content provider and the CDN service provider. When an end-user requests relevant content, the content routing server of a CDN redirects the request to an edge node close to that end-user based on pre-defined strategies and the edge node delivers the content to the end-user.
+
+These use cases are suitable for:
+
+- browsing static content, such as images, words, animations and audio/video content;
+- downloading files, such as articles, electronic books, application software and system software;
+- audio/video on demand, such as movies, TV programmes, music and songs.
+
+##### **7.1.1.2 Content upload**
+
+In this use case, end-users in different locations can upload their own content to the resource servers of one content provider via the nearest edge node selected by the CDN. This use case can accelerate user-generated content upload and distribution.
+
+#### **7.1.2 Dynamic content delivery**
+
+##### **7.1.2.1 Dynamic web content delivery**
+
+In this use case, a CDN chooses the most appropriate transmission path to deliver dynamic content, which is created during the use of an application.
+
+This use case is suitable for, but not limited to, delivery of dynamic content created by a certain application, such as active server pages, hypertext preprocessor pages, Java server pages and Java pages.
+
+##### **7.1.2.2 Live content distribution**
+
+In this use case, live content can be distributed to multiple edge nodes by a CDN, then delivered to a large number of end-users to save the bandwidths of backbone networks and provide better QoE when the multicast network is not available.
+
+This use case is suitable for, but not limited to, movie or music broadcast, live and advertisement broadcast and live text content distribution services.
+
+#### **7.1.3 Mixed content distribution**
+
+The CDN can also provide a distribution service for a mixture of static and dynamic contents. In this case, static content can be distributed and stored in the CDN edge nodes as normal. Dynamic content can be retrieved from its original source by choosing an optimal routing path based on relevant strategies. The CDN then synchronizes dynamic and relevant static contents, displaying them on end-user terminals.
+
+#### **7.1.4 Virtual private content delivery network**
+
+Some content providers or companies may have special requirements for their content distribution, using a private CDN solution within a specific area over a given period of time. They want control and management of the private CDN themselves, without their own CDN solutions.
+
+In this use case, CDN providers can provide virtual private CDNs to their customers by creating certain logical CDN partitions from the entire CDN resource, e.g., a combination of certain CDN hardware and software resources, with sufficient capabilities based on customer demand.
+
+#### **7.1.5 Authentication acceleration**
+
+For security issues, authentication, such as that for a user identifier, needs to be processed by the original resource server, which increases the pressures of processing on that server and backbone networks.
+
+In this use case, relevant authentication can be processed in a CDN, instead of the original resource server, subject to agreement between the CDN and content providers. This solution can accelerate authentication and reduce access pressure on the original resource.
+
+This use case is suitable for, but not limited to, hypertext transfer protocol secure services.
+
+#### **7.1.6 Services across different networks**
+
+In this use case, services provided by a content provider can be accessed by end-users from a CDN across different networks, such as a fixed or mobile network, or the CDNs provided by different CDN operators.
+
+## **7.2 Capability use cases**
+
+#### **7.2.1 Content processing**
+
+In this use case, content processing services, such as image reformation, audio-visual content transcoding, popular content updating and small file converging, are provided by redundant data-processing capabilities within a CDN.
+
+#### **7.2.2 Statistic or monitoring service**
+
+In this use case, a CDN can provide statistical results of content access and report possible safety threats within a period of time by analysing end user access log data, according to content provider requirements. A CDN can also provide report network traffic status to network operators by analysing the network traffic data of their carrier networks, which is collected when it provides content delivery services.
+
+#### **7.2.3 Resource rental services**
+
+In this use case, a CDN is able to store or cache user digital resources in their CDN nodes based on user requirements by using redundant storage resources. This use case includes, but is not limited to, content storage or caching services and pre-located storage or caching services.
+
+# **8 Requirements**
+
+## **8.1 General requirements**
+
+### **8.1.1 Requirements for delivering various types of content**
+
+GR01: A CDN is recommended to have the capabilities of delivering various types of content, such as text, picture, audio-video and cartoon.
+
+GR02: A CDN is recommended to have the capability of delivering static, dynamic or mixed content.
+
+### **8.1.2 Requirements for accessing by multiple types of device**
+
+GR03: A CDN is recommended to have access capabilities by multiple types of device, e.g., personal computer, intelligent mobile device, personal assistant device and television with set top box.
+
+#### **8.1.3 Requirements for supporting multiple protocols**
+
+GR04: A CDN is recommended to have capabilities to support multiple protocols.
+
+### **8.1.4 Requirements for content delivery network service, and node management and maintenance**
+
+GR05: A CDN is recommended to have capabilities to maintain and manage the relevant status of services or nodes, e.g., connection quality and node status.
+
+#### **8.1.5 Requirements for probing the carrier networks**
+
+GR06: A CDN is optionally to have capabilities of probing carrier network performance to improve service quality.
+
+#### **8.1.6 Requirements for content cache or storage**
+
+GR07: A CDN is required to have capabilities to store or cache content within its service coverage area based on a pre-defined storage or cache policy.
+
+#### **8.1.7 Requirements for request routing**
+
+GR08: A CDN is recommended to have capabilities to redirect requests to edge nodes nearby end-users.
+
+CR09: A CDN is recommended to have capabilities to select the most appropriate routing path, such as the best connection quality and shortest path.
+
+## **8.2 Service-oriented requirements**
+
+#### **8.2.1 Requirements for synchronization of mixed content delivery**
+
+SOR01: A CDN is recommended to have capabilities to keep static and dynamic contents synchronous.
+
+### **8.2.2 Requirements for providing virtual private content delivery network**
+
+SOR02: A CDN can optionally have capabilities to insulate a logical partition from CDN resources and to provide a virtual private CDN independently.
+
+#### **8.2.3 Requirements for original authentication acceleration**
+
+SOR03: A CDN can optionally have capabilities to provide an original authentication proxy granted by the original content source based on relevant agreements between the CDN and original content providers.
+
+#### **8.2.4 Requirements for providing services across different networks**
+
+SOR04: A CDN can optionally connect to different networks, such as the fixed and mobile networks, or the CDNs provided by different CDN operators.
+
+#### **8.2.5 Requirements for content processing services**
+
+SOR05: A CDN can optionally have capabilities to transfer the content format from one content processing service to another, e.g., different content coding, size and resolution.
+
+SOR06: A CDN can optionally have capabilities to encrypt content based on content provider demand.
+
+#### **8.2.6 Requirements for statistical analysis services**
+
+SOR07: A CDN can optionally have capabilities to analyse statistically services provided by content providers.
+
+#### **8.2.7 Requirements for the reporting of network performances**
+
+SOR08: A CDN can optionally have capabilities to analyse network performance and to provide statistical performance reports about the networks.
+
+#### **8.2.8 Requirements for providing resource rental services**
+
+SOR09: A CDN can optionally have capability to provide its data storage or caching spaces to consumers.
+
+## **8.3 Requirement for security**
+
+### **8.3.1 Security requirements for contents**
+
+SR01: A CDN is required to provide measures to guarantee consistency of content data when content is delivered from the content resource to the user.
+
+SR02: A CDN is required to provide measures to prevent unauthorized access to the content delivered.
+
+SR03: A CDN can optionally provide a digital rights management service when needed.
+
+#### **8.3.2 Security requirements for components of multimedia content delivery network**
+
+SR04: A CDN is recommended to provide measures to prevent its components from attacking and invading.
+
+SR05: A CDN is recommended to configure redundancy to maintain services if certain components become unavailable.
+
+#### **8.3.3 Security and privacy requirements for user information**
+
+SR06: A CDN is required to provide measures to prevent private user and service provider information of, such as username, password and content consumed, from unauthorized exposure.
+
+## Bibliography
+
+- [b-ITU-T H.780] Recommendation ITU-T H.780 (2012), *Digital signage: Service requirements and IPTV-based architecture.*
+- [b-ITU-T Y.2084] Recommendation ITU-T Y.2084 (2015), *Distributed service networking content distribution functions.*
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.746**
+
+(06/2012)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Audiovisual services
+
+# --- **Requirements of multimedia optimization control components**
+
+Recommendation ITU-T F.746
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in a blue sans-serif font, with "ITU" in a larger, bold font above it.
+
+ITU logo
+
+International  
+Telecommunication  
+Union
+
+## ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>AUDIOVISUAL SERVICES</b>                                     | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>HUMAN FACTORS</b>                                            | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.746
+
+# Requirements of multimedia optimization control components
+
+## Summary
+
+Recommendation ITU-T F.746 defines multimedia optimization control components (MOCCs), which can provide guidance services to multimedia applications and services in the process of service node selection, traffic optimization, performance enhancement, etc. This Recommendation specifies the MOCC requirements and defines a MOCC functional model. Some typical MOCC deployment scenarios are also described.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T F.746    | 2012-06-29 | 16          |
+
+## Keywords
+
+Control component, multimedia applications, multimedia services, optimization.
+
+# FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2013
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                     | Page |
+|---------------------------------------------------------------------|------|
+| 1 Scope .....                                                       | 1    |
+| 2 References.....                                                   | 1    |
+| 3 Definitions .....                                                 | 1    |
+| 3.1 Terms defined elsewhere .....                                   | 1    |
+| 3.2 Terms defined in this Recommendation.....                       | 1    |
+| 4 Abbreviations.....                                                | 2    |
+| 5 Overview .....                                                    | 2    |
+| 6 Functional architecture .....                                     | 2    |
+| 7 Requirements .....                                                | 4    |
+| 7.1 General requirements.....                                       | 4    |
+| 7.2 MOCC service discovery requirements.....                        | 4    |
+| 7.3 Transport information collection requirements .....             | 5    |
+| 7.4 Interaction and information exchange requirements .....         | 5    |
+| 7.5 Security requirements .....                                     | 5    |
+| Appendix I – MOCC deployment scenarios .....                        | 6    |
+| I.1 MOCC deployment in distributed file share services systems..... | 6    |
+| I.2 MOCC deployment in the streaming services systems .....         | 10   |
+| I.3 MOCC deployment in NAT traversal and media relay .....          | 14   |
+
+
+
+# Requirements of multimedia optimization control components
+
+# 1 Scope
+
+The multimedia optimization control components (MOCCs) defined in this Recommendation are assistance entities which can obtain reliable information from the underlying network. This sort of information can be fed to multimedia applications and services and used as guidance services in the process of service node selection, data traffic optimization and performance enhancement. The MOCC component is located between the multimedia applications and services layer and the network layer. MOCC entities will not be involved in actual data relay and transmission.
+
+The MOCC components can be deployed either in distributed multimedia systems or traditional client-server systems. They can be used in various networks such as NGN [ITU-T Y.2012], internet and other distributed systems.
+
+This Recommendation specifies requirements according to some typical scenarios.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T F.700] Recommendation ITU-T F.700 (2000), *Framework Recommendation for multimedia services*.
+- [ITU-T F.701] Recommendation ITU-T F.701 (2000), *Guideline Recommendation for identifying multimedia service requirements*.
+- [ITU-T Y.2012] Recommendation ITU-T Y.2012 (2010), *Functional requirements and architecture of next generation networks*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation does not use any terms defined elsewhere.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 supernode:** A peer in the overlay network that offers services, including message routing, to other members or clients of the overlay network.
+
+**3.2.2 tracker:** An index server that can assist in the communication between peers in some peer-to-peer file sharing and multimedia systems by collecting information of file replicas and then providing the corresponding information to the resource demanders to initiate a download.
+
+# 4 Abbreviations
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                            |
+|------|--------------------------------------------|
+| AS   | Autonomous System                          |
+| CDN  | Content Delivery Network                   |
+| DOS  | Denial of Service                          |
+| ID   | Identity                                   |
+| IP   | Internet Protocol                          |
+| IPv4 | Internet Protocol version 4                |
+| IPv6 | Internet Protocol version 6                |
+| ISP  | Internet Service Provider                  |
+| MOCC | Multimedia Optimization Control Component  |
+| NAT  | Network Address Translation                |
+| NGN  | Next Generation Network                    |
+| NLRF | Node Location Resolution Function          |
+| P2P  | Peer to Peer                               |
+| PoP  | Point of Presence                          |
+| RASF | Resource Awareness and Statistics Function |
+| TCP  | Transmission Control Protocol              |
+| VoIP | Voice over Internet Protocol               |
+
+# 5 Overview
+
+Due to the evolution of network and multimedia technologies, multimedia services are developing rapidly both on the system scale and on the volume of users, especially for services on the Internet. In contrast with traditional centralized service provision models, more and more services and applications tend to be deployed as distributed models, meaning that the data are transmitted along the paths established among nodes distributed across the whole network. Web content distribution, P2P streaming and P2P file sharing are typical examples of distributed models. For most distributed networks, each node should select one or more service providing nodes from a set of candidates to acquire the desired resources. However, under the end-to-end principle, applications and underlying networks are separated except on the end nodes. Therefore, the "selection" might be random, since the applications may not have the reliable information from transport networks such as topology, congestion status and network address translation (NAT) installation. Sometimes, nodes may cross several network boundaries to fetch the desired resources, thus generating a large amount of costly cross-ISP traffic.
+
+MOCCs defined in this Recommendation are complementary entities that can collect reliable information from the underlying network, analyse it and provide guidance services to the multimedia applications and services (see [ITU-T F.700] and [ITU-T F.701]) in the process of service node selection, data traffic optimization and performance enhancement.
+
+# 6 Functional architecture
+
+Conceptually, multimedia optimization control components are located between the application and service layer and the network layer. The MOCC functional model is illustrated in Figure 1. It is composed of an MOCC server and MOCC clients.
+
+The MOCC server, which resides on the network side, is responsible for collecting and analysing the information from the underlying transport network, and for providing the processed information to multimedia services and applications and to the MOCC client. The MOCC server consists of an entrance component, a node location resolution function (NLRF) and a resource awareness and statistics function (RASF).
+
+![Figure 1 – Functional architecture for multimedia optimization control components. The diagram shows a central 'MOCC server' block containing 'MOCC entrance', 'Node location resolution function (NLRF)', and 'Resource awareness and statistics function (RASF)'. Above it, 'Multimedia services/applications' connect via interface I_a. Below the server, 'Underlying transport networks' connect via interface I_b. To the left, an 'End-user' block contains a 'MOCC client' which connects to the server via interface I_c. To the right, 'Other networks' connect via interface I_d. A thick horizontal line with diagonal hatching separates the server from the underlying transport networks. The label F.746(12)_F01 is in the bottom right corner.](acfc53eca625d62b38aa2563efa95c3e_img.jpg)
+
+Figure 1 – Functional architecture for multimedia optimization control components. The diagram shows a central 'MOCC server' block containing 'MOCC entrance', 'Node location resolution function (NLRF)', and 'Resource awareness and statistics function (RASF)'. Above it, 'Multimedia services/applications' connect via interface I\_a. Below the server, 'Underlying transport networks' connect via interface I\_b. To the left, an 'End-user' block contains a 'MOCC client' which connects to the server via interface I\_c. To the right, 'Other networks' connect via interface I\_d. A thick horizontal line with diagonal hatching separates the server from the underlying transport networks. The label F.746(12)\_F01 is in the bottom right corner.
+
+**Figure 1 – Functional architecture for multimedia optimization control components**
+
+The functions of MOCC server components are as follows:
+
+- **MOCC entrance component:** The MOCC entrance component provides registration and service discovery functions for NLRF, RASF and the MOCC client. NLRF and RASF should register its address, policies, server status and other information with the MOCC entrance component. In order to select the optimum service providing nodes, since there might be multiple MOCC servers in the network, the client should be first authenticated to the MOCC entrance component, which will be responsible for providing the client with the address of the most promising NLRF and RASF. The MOCC entrance component has interfaces with NLRF, RASF, as well as the MOCC clients.
+- **NLRF and RASF:** NLRF and RASF can provide the guidance service or node selection service to applications by collecting and analysing the information of the underlying network. In practice, the NLRF and RASF can be implemented in one physical MOCC server. Network operators can deploy multiple MOCC servers with multiple instances of NLRF and RASF. The information of NLRF and RASF can be maintained by the MOCC entrance component. Some policies may be set for the clients to access NLRF and RASF.
+
+By collecting the information of the underlying network in real time, the MOCC servers could obtain reliable information, such as static topology of the whole network (maintained by NLRF) or dynamic network status (maintained by RASF).
+
+- **Network deployment information:** This information is relatively stable, for example, link capacities, node locations and adjacency relationships of the service nodes, and NAT installations. Furthermore, basic information of the service nodes and some policies enforced by the carriers may also be included in network deployment information. This kind of information is collected and maintained by NLRF.
+- **Network resource status information:** This information includes bandwidth-related data, congestion status of links, etc. This kind of information is more dynamic than network deployment information and can be used as a basis for load balancing and traffic optimization. This kind of information is collected and maintained by RASF.
+
+The MOCC client is embedded in the end user device and is responsible for communicating with the MOCC server to acquire information (through interface  $I_c$  in Figure 1) for multimedia service and application optimization.
+
+Multimedia optimization control components (MOCC server and MOCC client) have interfaces with the multimedia service and application control entities ( $I_a$  in Figure 1), by which the multimedia system can acquire the necessary information from the transport network layer. In addition, those components should have interfaces with the transport network layer ( $I_b$  in Figure 1), through which they can collect and analyse the transport information according to the requirements of the given service.
+
+# 7 Requirements
+
+## 7.1 General requirements
+
+**GEN-110:** The MOCC can be installed on centralized servers, or can be installed on multiple servers across the whole network. In any case, it should provide an interface to multimedia applications and services. The network information provided by the MOCC component should be accurate and reliable.
+
+**GEN-120:** Under the P2P application context, according to the particular mechanism, the MOCC server should be able to be queried by the normal peers as well as by the P2P index servers. MOCCs should be suitable for different P2P systems and protocols, a general interface should be defined between MOCC and those applications.
+
+**GEN-130:** MOCCs should be able to process massive requests from the applications with reasonable and acceptable response time. Specific performance requirements shall be fulfilled. Those requirements may include, amongst others, response time, efficiency, and query precision.
+
+**GEN-140:** MOCCs are independent from specific multimedia systems and they should not have any impact on the implementation and performance of the multimedia services when guidance services are unavailable or MOCC components fail.
+
+**GEN-150:** MOCC services provided by different service providers or network operators should be able to interoperate with one another.
+
+**GEN-160:** Information of the underlying network provided by the MOCC services should be maintained in the local entities of the multimedia system, so as to reduce the network load caused by the frequent queries.
+
+**GEN-170:** MOCCs should have a mechanism to protect the user privacy, some essential network operator information, and sensitive information collected from the bearer networks. It should also have a mechanism to protect themselves against DOS attacks.
+
+## 7.2 MOCC service discovery requirements
+
+**SDR-110:** Public MOCC servers are necessary to help address and policy registration.
+
+**SDR-120:** MOCC clients should be authenticated before attempting to query MOCC servers.
+
+**SDR-130:** MOCC clients should cache the replies from MOCC servers and avoid sending replicated query requests. This method helps lowering the processing burden on the MOCC server caused by the translation from IP addresses to network location identification. However, it should be noted that cache may be unreasonable in mobile scenarios.
+
+**SDR-140:** To clearly define the discovery procedure, specification of discovery interface and corresponding protocol should be standardized.
+
+## **7.3 Transport information collection requirements**
+
+Information of the underlying network that should be collected by MOCC servers includes *inter alia*:
+
+**TIC-110:** Network topology includes network domain, network location properties, neighbourhood relationship, bandwidth between domains, route costs, etc. Network location properties should include network operator name, AS number, PoP, IP prefix, IP address, etc.
+
+**TIC-120:** Alternatives of network operator's traffic engineering policy (network policy).
+
+**TIC-130:** Network static information, such as network capacities, locations and adjacency relationships of the service node and the endpoints, the NAT installations and so on.
+
+**TIC-140:** Network dynamic information, such as the bandwidth-related information, the congestion status of the links and so on.
+
+## **7.4 Interaction and information exchange requirements**
+
+**IIE-110:** Information exchanged between the MOCC client and MOCC server may include information such as access authentication, network location search, network distance search, and network capacity search.
+
+**IIE-120:** In the interaction between MOCC client and MOCC entrance, the MOCC client sends a request including information about itself such as identification or IP address to MOCC server; MOCC entrance replies one or more MOCC server's address to the authorized client.
+
+**IIE-130:** In the interaction between MOCC server and MOCC entrance, the MOCC entrance should have MOCC server's address and policies information; this should be controlled by the network operator. MOCC entrance should be able to query the MOCC server's status, including busy, failure, and normal.
+
+**IIE-140:** Within the MOCC server, interaction of information includes transport network information synchronization and client request forwarding.
+
+## **7.5 Security requirements**
+
+**SEC-110:** MOCC server should keep the network information and content secret, and it should take measures to protect the privacy of the MOCC client end users.
+
+**SEC-120:** Appropriate methods should be deployed to prevent attacks targeted at MOCC servers.
+
+**SEC-130:** An authentication mechanism should be used between the MOCC server and network operator in order to establish a trust relationship between these two entities.
+
+# Appendix I
+
+## MOCC deployment scenarios
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### I.1 MOCC deployment in distributed file share services systems
+
+#### I.1.1 General description
+
+Distributed file sharing applications are very common in the Internet and have developed rapidly in recent years. Their prominent advantages are high efficiency and reliability because the services and resources are distributed across the whole network so that each peer can acquire different file replicas from multiple candidates. Therefore, file exchanging is becoming more flexible than before. Among these file sharing systems, the most prevalent method is to use P2P overlay technologies to implement file sharing applications amongst the peers in networks. Depending on whether the P2P overlay network is used for control message propagation or for data transmission, the P2P file sharing systems can be classified into two categories.
+
+**Category A:** In the first category, the P2P overlay network is only used for control message propagation: Namely, search and response messages are propagated along paths in this overlay network. However, once the search results are available, real data transmission occurs directly between the peers on the underlying physical network, regardless of the overlay network. In this category, searching is the most important architectural issue. According to the different search mechanisms, we can further divide the distributed file-sharing systems in this category into three subtypes:
+
+- **Centralized directory model:** This means that all the files or resources are indexed in a centralized server or a handful of centralized servers.
+- **Fully decentralized model:** This means that all the directory services and resources are fully decentralized on every peer of the whole network. Distributed search algorithms often use flooding query method to look for file information.
+- **Hybrid model:** This is the combination of the above two types. One implementation is to divide the peers in the network into several groups, and in each group, the node with good performance and high bandwidth will be selected as the directory server, which is typically called a supernode. It is responsible for the maintenance of the whole directory of the group and connects to other supernodes from the overlay network being used for searching.
+
+**Category B:** In the second category, the peers form a cooperative overlay network for data exchange. Data blocks are transmitted along paths in this overlay network.
+
+On the application side, deployment of the MOCC functionalities may happen at different levels. For example, in a completely decentralized network, selection of the best sources is totally up to the user. In Category B P2P systems, central elements such as trackers or servers act as mediators. Therefore, in the former case, improvement would require modification in applications, while in the latter case, it could be implemented just in some central elements. The following clause presents and analyses the scenarios using the different file sharing system types.
+
+#### I.1.2 Scenario 1: Centralized or hybrid model
+
+**Description:** The scenario in Figure I.1 fits within either the centralized or the hybrid model, in which the centralized index server or the supernode can serve as mediator for the end users. User A wants to download a resource R. In this scenario, it assumes that the centralized server or the supernodes only provide the index service to the nodes, which won't provide any policies regarding the traffic optimization to the users.
+
+**Pre-condition:** A number of copies of resource R are scattered in the network. In the centralized model, all the resources are indexed in the centralized server. In the hybrid model, the supernode indexes all the resources located in directly connected non-supernode peers. The centralized server or all the supernodes are authorized to use the MOCC service. NLRF and RASF have already been registered to the MOCC entrance component, which has created the corresponding records in turn.
+
+![Figure I.1 – File sharing systems scenario using MOCC service. The diagram is divided into two parts: (a) Centralized model and (b) Hybrid model. Both parts show a 'Service/application stratum' at the top containing 'MOCC entrance', 'NLRF', and 'RASF' components. Below this is a 'Bearer network information' cloud. In (a), a 'Centralized server' is connected to the cloud and three 'User' nodes. In (b), three 'Supernode' nodes are connected to the cloud, each connected to one or more 'User' nodes. Arrows indicate data flow between the strata and the network information cloud, and between the cloud and the servers/supernodes.](4e4be0bd8b235167902f2c03e41da651_img.jpg)
+
+Figure I.1 – File sharing systems scenario using MOCC service. The diagram is divided into two parts: (a) Centralized model and (b) Hybrid model. Both parts show a 'Service/application stratum' at the top containing 'MOCC entrance', 'NLRF', and 'RASF' components. Below this is a 'Bearer network information' cloud. In (a), a 'Centralized server' is connected to the cloud and three 'User' nodes. In (b), three 'Supernode' nodes are connected to the cloud, each connected to one or more 'User' nodes. Arrows indicate data flow between the strata and the network information cloud, and between the cloud and the servers/supernodes.
+
+(a) Centralized model
+
+(b) Hybrid model
+
+F.746(12)\_FI.1
+
+**Figure I.1 – File sharing systems scenario using MOCC service**
+
+In this scenario:
+
+- 1) The centralized server or supernodes send the MOCC matching request to the MOCC entrance component, which includes the addresses of the centralized server or the supernodes. On receiving the requests, the MOCC entrance component will then authenticate them to identify if they are legal clients.
+- 2) After the authentication, the MOCC entrance component will look up for the authorized MOCC servers (RASF, NLRF) for the centralized server or supernodes and then send the addresses and server information in the response messages to the centralized server or supernodes.
+- 3) Upon receiving the messages, the server or the supernodes will cache those MOCC servers' information and then send the access request to the MOCC servers including their addresses and other authentication information until the authentication is succeeded.
+- 4) A user sends a search request to a centralized index server or its responsible supernode, say S.
+- 5) S executes the search (either searches a centralized database in case of the centralized model or initiates a search among the supernodes in the case of the hybrid model) and obtains the list of nodes that can satisfy the search request.
+- 6) S sends the transport network statistics query request to NLRF or RASF including the list of nodes mentioned above as well as the requesting node.
+- 7) NLRF or RASF ranks the list of nodes based on its knowledge of the carrier network status and returns the ranked list of nodes to S.
+
+- 8) S can return the ranked list of nodes to the requesting user or, alternatively, can choose the top ranked K nodes to return to the user.
+- 9) The user uses the ranked list of nodes to initiate the real file downloading. The user can request different ranges from different nodes to boost the downloading speed.
+
+#### I.1.3 Scenario 2: Decentralized scenario
+
+**Description:** The scenario in Figure I.2 illustrates the fully distributed file sharing system model, in which all resources are distributed in every peer of the whole network.
+
+**Pre-condition:** A number of copies of resource are scattered in the network. There is no centralized indexing server to index the resources. User A wants to download a resource R. All or a part of the users are authorized to use the MOCC service. NLRF and RASF have already been registered to the MOCC entrance component, which has created the corresponding records in turn.
+
+![Diagram of Figure I.2 showing the file sharing system scenario using MOCC service in the fully distributed model. The diagram is divided into three horizontal layers. The top layer, 'Service/application stratum', contains a 'MOCC entrance' box connected by a double-headed arrow to a dashed box containing 'NLRF' and 'RASF' boxes. The middle layer is a cloud labeled 'Bearer network information', connected to the top layer by double-headed arrows. The bottom layer shows five 'User' icons (laptops) connected to the 'Bearer network information' cloud. A small label 'F.746(12)_FI.2' is at the bottom right.](bd671b21db63e6fdb2196e9b18502aac_img.jpg)
+
+Diagram of Figure I.2 showing the file sharing system scenario using MOCC service in the fully distributed model. The diagram is divided into three horizontal layers. The top layer, 'Service/application stratum', contains a 'MOCC entrance' box connected by a double-headed arrow to a dashed box containing 'NLRF' and 'RASF' boxes. The middle layer is a cloud labeled 'Bearer network information', connected to the top layer by double-headed arrows. The bottom layer shows five 'User' icons (laptops) connected to the 'Bearer network information' cloud. A small label 'F.746(12)\_FI.2' is at the bottom right.
+
+**Figure I.2 – File sharing systems scenario using MOCC service in the fully distributed model**
+
+In this scenario:
+
+- 1) The user sends the MOCC matching request to the MOCC entrance component, which includes its address, etc. On receiving the request, the MOCC entrance component will then authenticate the user to identify if they are legal clients.
+- 2) After the authentication, the MOCC entrance component will look up for the authorized MOCC servers (RASF, NLRF) for the user, and then send the addresses and server information in the response messages to the user.
+- 3) Upon receiving the messages, the user will cache those MOCC servers' information and then send the access request to the MOCC servers, which include its address and other authentication information until the authentication is succeeded.
+- 4) The user initiates a search request to the system.
+- 5) The system returns a list of nodes that can satisfy the search request to the user.
+- 6) The user sends the transport network statistics query request to NLRF or RASF, including the list of nodes mentioned above.
+- 7) NLRF or RASF ranks the list of nodes based on its knowledge of the carrier network status, and returns the ranked list of nodes to the user.
+- 8) The user uses the ranked list of nodes to initiate the real file downloading. The user can request different ranges from different nodes to accelerate the downloading speed.
+
+#### I.1.4 Scenario 3: P2P with real data exchange among peers
+
+**Description:** The scenario in Figure I.3 illustrates file downloading in P2P system with data exchange among peers. User 1 is looking for the "seed" for a particular movie in this kind of P2P network. Trackers 1 and 2 are connected to the MOCC service. Since the algorithms and mechanisms vary in different kinds of hybrid file sharing systems, the tracker capabilities in those systems are diversified. This scenario assumes that Trackers 1 and 2 only provide the collection and index services to the nodes, which will not provide any policies regarding the traffic optimization to the users.
+
+**Pre-condition:** The "seed" (.torrent) file has been already published and the file information has been registered in Trackers 1 and 2. Trackers 1 and 2 are responsible for the maintenance of status of all the peers in its group and nodes-selection of the given resources. All the trackers in Category B P2P system are authorized to use the MOCC service. NLRF and RASF have already registered with the MOCC entrance component, which has in turn created the corresponding records. Trackers 1 and 2 are authorized to use the MOCC services to optimize their node selection.
+
+![Diagram illustrating the file sharing application optimization scenario using MOCC services. The diagram shows a hierarchy of components: at the top, a 'MOCC entrance' box is connected to a dashed box containing 'NLRF' and 'RASF' components. This dashed box is connected to a 'Bearer network information' box. Below the MOCC entrance, 'Tracker 1' and 'Tracker 2' are shown as server icons. Both trackers have bidirectional arrows connecting them to the MOCC entrance. 'User 1' is shown as a client icon connected to 'Tracker 1'. There are also icons representing other peers connected to both 'Tracker 1' and 'Tracker 2'. A label 'F.746(12)_Fl.3' is present in the bottom right corner of the diagram area.](7efae06af3af43ffe5d4b956a679cf54_img.jpg)
+
+Diagram illustrating the file sharing application optimization scenario using MOCC services. The diagram shows a hierarchy of components: at the top, a 'MOCC entrance' box is connected to a dashed box containing 'NLRF' and 'RASF' components. This dashed box is connected to a 'Bearer network information' box. Below the MOCC entrance, 'Tracker 1' and 'Tracker 2' are shown as server icons. Both trackers have bidirectional arrows connecting them to the MOCC entrance. 'User 1' is shown as a client icon connected to 'Tracker 1'. There are also icons representing other peers connected to both 'Tracker 1' and 'Tracker 2'. A label 'F.746(12)\_Fl.3' is present in the bottom right corner of the diagram area.
+
+**Figure I.3 – File sharing application optimization scenario using MOCC services**
+
+In this scenario:
+
+- 1) Trackers 1 and 2 send the MOCC matching request to the MOCC entrance component, which includes the Tracker ID, addresses, etc. On receiving the requests, the MOCC entrance component will try to authenticate those trackers to identify if they are legal clients.
+- 2) After the authentication, the MOCC entrance component will look up for the authorized MOCC servers (RASF, NLRF) for those trackers, and then send the addresses and server information in the response messages to the trackers.
+- 3) Upon receiving the messages, Tracker 1 and 2 will cache that MOCC server information and then send an access request to the MOCC servers until the authentication is successful. The access request includes tracker ID, address and other authentication information.
+- 4) User 1 gets one "seed" (.torrent) of the movie, which includes the available tracker information. User 1 sends the connect attempts to those trackers on the list one by one until one successful connection has been established between it and a tracker, say Tracker 1.
+- 5) Corresponding to the given movie, Tracker 1 retrieves a huge list of candidate peers, which are recorded storing one or more replicas. In the normal Category B P2P operation, the tracker will send the list to User 1, who will then randomly choose some of the candidate peers. However, with the aid of the MOCC server, that selection can be optimized.
+
+- 6) Tracker 1 will send the transport network statistics query request, which includes the information of those candidate peers. The type of request can be one or a combination of: network location query request, network distance query request and network resources status query request. Those requests are preceded by NLRP and RASP, respectively.
+- 7) According to the different query requests, NLRP and RASP will then inquire about the bearer network information services, which can be implemented by the MOCC itself or can be provided by some practical entities such as RACF. In some cases, within certain policy boundaries, network information services can be provided by the network operators.
+- 8) MOCC servers send the results to the trackers to initiate the node selection optimization.
+- 9) The tracker sends the optimized node list to User 1.
+- 10) User 1 will send a TCP connect request to the nodes on the list. After successful connections have been established, a handshake procedure will be performed among those peers. After that, those peers use "interested", "not interested", "choke", "unchoke" to exchange the attitude of resource sharing.
+- 11) The Category B P2P file transfer begins.
+- 12) The TCP connections tear down among the peers after the file has been fully downloaded.
+
+### I.2 MOCC deployment in the streaming services systems
+
+#### I.2.1 General description
+
+The conventional centralized client/server-based streaming media system has some inherent limitations that make it impossible to be widely deployed, such as server performance bottleneck and single point of failure. Comparing to the client/server-based system, streaming media systems based on distributed content delivery networks can somehow improve the service capability. However, there are still issues (such as expensive hardware deployment, high bandwidth cost and complicated device management and scalability) that add to the complexity and cost of implementations.
+
+Another radical way to improve the scalability of the streaming services is based on P2P technology. However, systems based on P2P-based streaming services cannot guarantee user experience. Factors include long start-time, topology inconsistency, instability induced by fast user turn-over ("churn") and NAT-deployment issues.
+
+The deployment of MOCC in P2P networks is to some extent helpful for solving those inherent problems. For example, RASP can record every resource contained by the node and NLRP can give the location information about the resource requested by any node.
+
+#### I.2.2 Scenario for P2P streaming media systems
+
+P2P file sharing systems have become common in the Internet. P2P technologies bring revolutionary changes to the network content distribution model and make it possible that the comprehensive streaming media applications become practical in the Internet.
+
+P2P streaming media systems use P2P technologies to alleviate the server load and optimize the service capability. Based on the type of data distribution method, most of the P2P streaming systems can be classified into two subtypes:
+
+- **Tree-based system:** This kind of P2P streaming system implements a tree-based content distribution, and the tree is in the application layer and rooted at the content sources. In principle, each node receives data from a parent node, which might be the source or a peer. If peers do not change frequently, then the systems require little message overhead since the packets are forwarded from node to node without the need for extra messages. However, in high-churn environments (i.e., fast turnover of peers in the tree), the tree must be continuously destroyed and rebuilt, which produces considerable control message overhead.
+
+- **Mesh-based system:** In this kind of P2P streaming system, each node contacts a subset of peers to obtain a number of chunks. Every node needs to know which chunks are owned by its peers and explicitly "pulls" the chunks it needs. This type of scheme involves overhead, due in part to the exchange of buffer maps between nodes (i.e., nodes advertise the set of chunks they have) and in part to the "pull" process (i.e., each node sends a request to receive the chunks). Each node relies on multiple peers to retrieve content and as a consequence mesh-based systems offer good resilience to node failure.
+
+Both tree-based and mesh-based systems have advantages in particular scenarios, but neither can completely overcome the challenges of the dynamic peer-to-peer environments. A strong advantage for mesh-based systems is their simplicity, but they have a trade-off between overhead and latency: if nodes choose to send notifications upon every segment arrival, then the overhead will increase; on the other hand, periodic notifications containing buffer maps reduce the overhead but increase latency. A tree-based system does not suffer from this trade-off, but has to face the inherent instability of dynamic environments and bandwidth underutilization.
+
+The deployment of MOCC in P2P streaming media systems can make the node acquire the information about the overlay network and its neighbours, which is useful to determine the status of the network and the correlative peers so as to make the right data schedule and relationship selection.
+
+##### **1.2.2.1 Scenario for tree-based systems**
+
+Tree-based systems have well-organized overlay structures (typically trees) for delivering data, with each data packet being disseminated using the same structure. Nodes on the structure have well-defined relationships, such as "parent-child" relationships in trees. Tree-based systems are typically push-based, i.e., when a node receives a data packet, it also forwards the copies of the packet to each of its children. Since all data packets follow this structure, it becomes critical to ensure that the structure is optimized to offer good performance to all receivers. Furthermore, the structure must be well-maintained, as nodes randomly join and leave the group. In particular, if a node crashes or otherwise stops performing adequately, all of its children in the tree will stop receiving packets, and the tree must be repaired. In addition, loop avoidance is an important issue that must be addressed when constructing tree-based structures in the streaming services system.
+
+**Description:** The scenario in Figure I.4 illustrates a tree-based system in which there is an application layer streaming tree with ten peers. In this scenario, it assumes that there are two peers at level 1 and receiving video directly from the server, four peers at level 2 receive video from their parents at level 1, and three of them forward received video to four peers at the bottom level.
+
+![Figure I.4: Tree-based system scenario using MOCC service with a single application layer multicast tree. The diagram shows a 'Service/application stratum' at the top containing 'MOCC entrance', 'NLRF', and 'RASF'. Below it is a 'Bearer network' cloud. A 'Server' is connected to the bearer network and to 'Peer 0'. 'Peer 0' is connected to 'Peer 2' and 'Peer 3'. 'Peer 2' is connected to 'Peer 6' and 'Peer 7'. 'Peer 3' is connected to 'Peer 8'. 'Peer 8' is connected to 'Peer 4'. 'Peer 4' is connected to 'Peer 1'. 'Peer 1' is connected to 'Peer 5'. 'Peer 5' is connected to 'Peer 9'. A thick orange line represents the multicast tree path: Server -> Peer 0 -> Peer 2 -> Peer 6 -> Peer 7 -> Peer 3 -> Peer 8 -> Peer 4 -> Peer 1 -> Peer 5 -> Peer 9. Peer 0 is circled in blue, and Peer 8 is circled in green. The label 'F.746(12)_FI.4' is at the bottom right.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+Figure I.4: Tree-based system scenario using MOCC service with a single application layer multicast tree. The diagram shows a 'Service/application stratum' at the top containing 'MOCC entrance', 'NLRF', and 'RASF'. Below it is a 'Bearer network' cloud. A 'Server' is connected to the bearer network and to 'Peer 0'. 'Peer 0' is connected to 'Peer 2' and 'Peer 3'. 'Peer 2' is connected to 'Peer 6' and 'Peer 7'. 'Peer 3' is connected to 'Peer 8'. 'Peer 8' is connected to 'Peer 4'. 'Peer 4' is connected to 'Peer 1'. 'Peer 1' is connected to 'Peer 5'. 'Peer 5' is connected to 'Peer 9'. A thick orange line represents the multicast tree path: Server -> Peer 0 -> Peer 2 -> Peer 6 -> Peer 7 -> Peer 3 -> Peer 8 -> Peer 4 -> Peer 1 -> Peer 5 -> Peer 9. Peer 0 is circled in blue, and Peer 8 is circled in green. The label 'F.746(12)\_FI.4' is at the bottom right.
+
+**Figure I.4 – Tree-based system scenario using MOCC service with a single application layer multicast tree**
+
+**Pre-condition:** The video files are sent along the established tree for the server to the last level peer. In this scenario, every peer will periodically send its overlay information to RASF, which includes next level peers, upper level peers, multicast tree ID, upload and download bandwidth, level ID, etc. The server or all the tree member peers are authorized to use the MOCC service. NLRF and RASF have already been registered to the MOCC entrance component, which has created the corresponding records in turn.
+
+In this scenario:
+
+- The MOCC servers are distributed in the network; therefore, each node who wants to use the MOCC functions should get access to the corresponding ones for the topologies information querying.
+- Together with the server, users belonging to the same session form an application-level multicast tree which is called a base tree, and the whole video file contained by the server is called a base stream. The members of the base tree periodically send the necessary information to MOCC entities, such as its parent and children, bandwidth, base stream information, etc. to renew the topology-related information for each one. When a new client wants to join the tree, for example, Peer 8, it will query the MOCC servers on the most suitable tree member (using some parent selection algorithm), and then it will join this tree.
+- Furthermore, if e.g., Peer 0 wants to leave the tree, it can send notification to the MOCC servers, in turn, the MOCC entities will notify Peer 0's parent and children and start to direct the repair for the tree.
+
+##### I.2.2.2 Scenario for mesh-based systems
+
+In a mesh-based P2P streaming system as illustrated in Figure I.5, peers are not confined to a comparative static topology. Instead, the peer relationships are established or terminated based on the content availability and bandwidth availability on peers. In the mesh-based structure, peers will dynamically connect to a subset of random peers in the system and will periodically exchange information about their data availability. Video content is pulled by a peer from its neighbours who have already obtained the content. Since multiple neighbours are maintained at any given moment,
+
+mesh-based video streaming systems are highly robust to peer churns. However, users may suffer from video playback quality degradation ranging from low video bit rates, long start-up delays, to frequent playback freezes because different data packets may traverse different routes to reach the users (this will also make it difficult to predict the variation of dynamic peer relationships).
+
+**Description:** Similar to P2P file sharing systems like Category B P2P, a mesh streaming system has a tracker to keep track of the active peers in the video session. Trackers 1 and 2 are all connected to the MOCC service. In this scenario, Trackers 1 and 2 provide index service for peers.
+
+**Pre-condition:** The video file has been already published and the file information has been registered in Trackers 1 and 2. Trackers 1 and 2 are responsible for the track of status of all the peers in its group and nodes-selection of the given resources. All the trackers in this system are authorized to use the MOCC service. NLRF and RASF have already registered to the MOCC entrance component, which have created the corresponding records in turn. Trackers 1 and 2 are authorized to use the MOCC services to optimize their nodes selection.
+
+![Diagram of a mesh-based system using MOCC service. The diagram is divided into three horizontal layers. The top layer, 'Service/application stratum', contains a 'MOCC entrance' box connected to a dashed box containing 'NLRF' and 'RASF' boxes. The middle layer is a cloud labeled 'Bearer network'. The bottom layer shows two trackers, 'Tracker 1' and 'Tracker 2', connected to each other and to the 'MOCC entrance' via the 'Bearer network'. Tracker 1 is connected to four peers: 'Peer 0', 'Peer 1', 'Peer 2', and 'Peer 3'. Tracker 2 is connected to four peers: 'Peer 4', 'Peer 5', 'Peer 6', and 'Peer 7'. Peers 0, 1, 2, and 3 are interconnected in a mesh. Peers 4, 5, 6, and 7 are also interconnected in a mesh. A label 'F.746(12)_FI.5' is present near Peer 6.](8fa679f79a1bb1f527cba9f29e784e89_img.jpg)
+
+Diagram of a mesh-based system using MOCC service. The diagram is divided into three horizontal layers. The top layer, 'Service/application stratum', contains a 'MOCC entrance' box connected to a dashed box containing 'NLRF' and 'RASF' boxes. The middle layer is a cloud labeled 'Bearer network'. The bottom layer shows two trackers, 'Tracker 1' and 'Tracker 2', connected to each other and to the 'MOCC entrance' via the 'Bearer network'. Tracker 1 is connected to four peers: 'Peer 0', 'Peer 1', 'Peer 2', and 'Peer 3'. Tracker 2 is connected to four peers: 'Peer 4', 'Peer 5', 'Peer 6', and 'Peer 7'. Peers 0, 1, 2, and 3 are interconnected in a mesh. Peers 4, 5, 6, and 7 are also interconnected in a mesh. A label 'F.746(12)\_FI.5' is present near Peer 6.
+
+**Figure I.5 – Scenario of the mesh-based system using MOCC service**
+
+In this scenario:
+
+- The MOCC servers are distributed in the network; therefore, each tracker who wants to use the MOCC functions should get access to the corresponding ones for the topologies information querying.
+- When one peer (for example Peer 3) joins the streaming session, Tracker 1 can query the network statistics information from the MOCC servers, which can be one or a combination of: network locations, network distance, network resources status query, etc. Tracker 1 then accordingly makes optimized active peers selections with the aid of the topologies information NLRF & RASF have been provided. After receiving an initial list of active peers, Peer 3 tries to make connections to some remote peers on the list and, after obtaining enough neighbours, Peer 3 will then start to exchange video content with its neighbours.
+
+### I.3 MOCC deployment in NAT traversal and media relay
+
+#### I.3.1 General description
+
+Many real-time communication services are using the distributed model, which can allow the users to establish direct media flows such as video, audio, text, etc. Unlike the client-server model, every host in a P2P network can act at the same time as server and client, and its peers are more or less equal. Therefore, the main problem for P2P applications in a NAT environment is that NATed peers are usually not reachable for arbitrary peers. Unsolicited connection requests from outside are denied by the NAT device because the requests are sent to the public internet address of the gateway and the NAT device has no clue to which internal address the request should be forwarded.
+
+![Diagram illustrating MOCC deployment in a hierarchical NATed environment. The diagram shows a hierarchy of NAT devices (NAT1 to NAT5) connected to the Internet. NAT1 is the root NAT with a public IP 202.112.100.100. NAT2, NAT3, NAT4, and NAT5 are connected to NAT1. Various nodes (Node A, Node B, Node C, Node D) and users (User A, User B, User C, User D) are connected to these NATs. A 'MOCC entrance' is connected to the Internet via 'NLRF' and 'RASF' components. A 'Bearer network information' box is shown in the Internet cloud. An inset on the right shows a list of NATs and their associated users: Node C (NAT3, USER = {User D}), Node D (NAT1, USER = {}), Node A (NAT2, USER = {}), Node B (NAT5, USER = {}), and NAT4 (USER = {User A, User C}).](81a4cbf0b3c4cbc065efdf8f800dadde_img.jpg)
+
+The diagram illustrates a hierarchical NAT environment. At the top, the Internet cloud contains a 'Bearer network information' box. Below it, NAT1 (public IP 202.112.100.100) is connected to the Internet. NAT1 has three internal interfaces: 10.10.1.\* connected to NAT2, 10.10.1.103 connected to NAT3, and 192.168.1.2 connected to NAT4. NAT2 (internal IP 10.10.1.100) is connected to Node D (internal IP 192.168.1.\*). NAT3 (internal IP 10.10.1.102) is connected to Node C (internal IP 172.24.1.\*). NAT4 (internal IP 192.168.1.1) is connected to Node A (internal IP 10.10.1.\*), User A, and User C. NAT5 (internal IP 10.10.1.\*) is connected to User D and Node B (internal IP 10.10.1.\*). A 'MOCC entrance' is connected to the Internet via 'NLRF' and 'RASF' components. An inset on the right shows a list of NATs and their associated users:
+
+- Node C: (NAT3, USER = {User D})
+- Node D: (NAT1, USER = {})
+- Node A: (NAT2, USER = {})
+- Node B: (NAT5, USER = {})
+- NAT4: (USER = {User A, User C})
+
+Diagram illustrating MOCC deployment in a hierarchical NATed environment. The diagram shows a hierarchy of NAT devices (NAT1 to NAT5) connected to the Internet. NAT1 is the root NAT with a public IP 202.112.100.100. NAT2, NAT3, NAT4, and NAT5 are connected to NAT1. Various nodes (Node A, Node B, Node C, Node D) and users (User A, User B, User C, User D) are connected to these NATs. A 'MOCC entrance' is connected to the Internet via 'NLRF' and 'RASF' components. A 'Bearer network information' box is shown in the Internet cloud. An inset on the right shows a list of NATs and their associated users: Node C (NAT3, USER = {User D}), Node D (NAT1, USER = {}), Node A (NAT2, USER = {}), Node B (NAT5, USER = {}), and NAT4 (USER = {User A, User C}).
+
+Figure I.6 – Illustration of MOCC deployed in the hierarchical NATed environment
+
+On the other hand, the peer-selecting methods in some P2P algorithms are somewhat random, which does not take the topology issues into consideration. This is especially the case when there are many NAT devices in the network and it is hard to get accurate estimation of those NATed peers connected to the Internet. Therefore, it might happen that in some systems the traffic is iteratively routed or takes a detour in case of the same-root NAT.
+
+In a general sense, the network resource controlled by one single NAT is within the boundary from its internal interface to the external interface of the lower-level NAT connected to it. There are no other NAT devices within this area, which is defined as the current network in this Recommendation. Regarding one NAT, the upper-level network, current network and lower-level network can be regarded as the directed edges, which compose the topology of the multi-level NATs deployment in a network. The NAT device whose external interface was configured with the global unique public address is called the root NAT (NAT1) as shown in Figure I.6. Along the edge, if there is one path from NAT1 to NAT2, then NAT1 can be called the same-root upper level NAT
+
+of NAT2; and meanwhile if there is another path from NAT1 to NAT3, then NAT2 and NAT3 are called same-root NAT to one another.
+
+According to the ownership of the NAT devices, the same-root NAT scenario can be divided into the following three categories:
+
+**Scenario 1:** In this scenario, all the NAT devices are deployed and maintained by the network operators, and the end users are not allowed to connect their own NATs to the network. One example of this scenario is the enterprise network.
+
+**Scenario 2:** In this scenario, there is one or more same-root NAT deployed, among which the lowest-level NATs are deployed by some users at liberty. This is very common in the campus network or public internet.
+
+**Scenario 3:** This scenario can be found in some broadband access provider network. There are some third-party NAT devices deployed in the operators' network, by which it can provide the access services to the end-users. In this scenario, users can deploy their own NAT devices as well.
+
+This clause discusses the above three scenarios respectively, which is illustrated with the example of the P2P VoIP system.
+
+The network deployment information collected by MOCC can provide assistance to solve this problem. For example, the address-related information of NAT can be used to implement the NAT traversal. On the other hand, to enhance the performance, it can help to find the best relay path, such as by minimizing the NATs in the path or discovering the same-root NATs.
+
+#### **I.3.2 Scenario 1: Unified NAT deployment by the network operators**
+
+**Description:** The scenario in Figure I.7 illustrates the deployment of MOCC functionalities into one P2P VoIP system. In this scenario, User D wishes to establish a call with User A. MOCC functionalities have been deployed into this system.
+
+**Pre-condition:** The P2P nodes in this system are authorized to use the MOCC service. NLRF and RASF have already registered to the MOCC entrance component, which has created the corresponding records in turn. User A and User D are registered to its corresponding bootstrapping servers.
+
+In this scenario:
+
+- 1) User D wants to establish a call with User A. First, it will send the location query request to its service node to acquire the address of User A.
+- 2) According to the UserID carried in the request message, the service node will then retrieve the IP address and NodeID of User A. The service node will then send the response message to User D, which includes the necessary information of User A.
+- 3) User D sends the session initiate request to the service node, which carries the address of User A.
+- 4) The simplest way for the service node to process this request is to choose some nodes along the path from User D to User A for the media relay. One possible path may be User D → Node C → Node D → User A. However, with the aid of the MOCC server, that selection can be optimized.
+- 5) The service node will send the network topology query request to the NLRF, which includes the information of those candidate nodes.
+- 6) NLRF will then inquire about the bearer network information services, which can be implemented by the MOCC itself or be provided by some practical entities such as RACF, or in some cases, within certain policy boundaries, those information services can be provided by the network operators, and then send the result to the service node.
+
+- 7) From the topology information, it was found that Node A and User A are under the same NAT, therefore the path can be established from User D → Node A → User A.
+
+![Diagram illustrating the scenario of P2P Application NAT traversal using MOCC service. The diagram shows a hierarchy of NAT devices (NAT1 to NAT5) connected to the Internet. NAT1 is connected to the Internet and has a public IP 202.112.100.100. NAT1 is connected to NAT2 (10.10.1.100) and NAT3 (172.24.1.*). NAT2 is connected to NAT4 (192.168.1.1) and NAT5 (192.168.1.2). NAT4 is connected to User A (10.10.1.*) and Node A. NAT5 is connected to Node D (10.10.1.*) and Node B. NAT3 is connected to Node C (10.10.1.102) and User D. The Internet cloud contains 'Bearer network information'. Above the Internet cloud, the MOCC entrance is connected to NLRF and RASF components.](08a978a124d3ed6cf1a3d0cfd89418d0_img.jpg)
+
+Diagram illustrating the scenario of P2P Application NAT traversal using MOCC service. The diagram shows a hierarchy of NAT devices (NAT1 to NAT5) connected to the Internet. NAT1 is connected to the Internet and has a public IP 202.112.100.100. NAT1 is connected to NAT2 (10.10.1.100) and NAT3 (172.24.1.\*). NAT2 is connected to NAT4 (192.168.1.1) and NAT5 (192.168.1.2). NAT4 is connected to User A (10.10.1.\*) and Node A. NAT5 is connected to Node D (10.10.1.\*) and Node B. NAT3 is connected to Node C (10.10.1.102) and User D. The Internet cloud contains 'Bearer network information'. Above the Internet cloud, the MOCC entrance is connected to NLRF and RASF components.
+
+**Figure I.7 – Scenario of P2P Application NAT traversal using MOCC service**
+
+#### I.3.3 Scenario 2: The lowest-level NATs are connected and owned by the users
+
+**Description:** The scenario in Figure I.8 illustrates the deployment of MOCC functionalities in a P2P VoIP system. MOCC functionalities have been deployed into this system. NAT-U1/U2/U3/U4 are owned and connected by the end-users, which remain unknown to the network operators.
+
+**Pre-condition:** The P2P nodes in this system are authorized to use the MOCC service. NLRF and RASF have already registered to the MOCC entrance component, which have created the corresponding records in turn. All the users are registered to its corresponding bootstrapping servers.
+
+In this scenario:
+
+- 1) The bootstrapping server is deployed in each level of this NAT topology, from the root NAT to the operator's lowest-level NATs, to which the user-owned NAT are connected. In this way, the NLRF can collect all the topology information of the end users.
+- 2) User A, User C and User D send the register request to the bootstrapping server in the current network of NAT2.
+- 3) Upon receiving those messages, the bootstrapping server will compare the address information carried in the IP headers and message payloads. If the information doesn't match, then it will determine that those users are behind the unknown NAT devices. And meanwhile it will store the address mapping information and send the message upwards level by level, until it reached the bootstrapping server in the public network.
+- 4) According to the topology information stored in each bootstrapping server, the topology view will be computed and generated by the NLRF component.
+
+- 5) User C wants to establish a call with User A. First, it will send the location query request to its service node to acquire the address of User A.
+- 6) The service node will send the network topology query request to the NLRF, which includes the information of User A and User C.
+- 7) NLRF will then query the bearer network information services, from the topology information. If it is found that User A and User C are under the same NAT, Node A can be selected as the optimum service node to assist the communication between User A and User C.
+- 8) After the path optimization, the media can be established from User A to User C.
+- 9) In this way, the unwanted traffic in the P2P system can be reduced, and the resources of the corresponding service node can be optimized as well.
+
+![Diagram illustrating network topology and NAT configurations for a P2P system. At the top, a MOCC entrance connects to a dashed box containing NLRF and RASF. An inset box shows a network topology with Node C, Node D, Node B, and Node A. Node C is connected to Node D and Node B. Node D is connected to Node A. Node B is connected to Node A. Associated with these nodes are state boxes: Node C: (-, USER = {}), Node D: (NAT3, USER = {User D}), Node B: (NAT1, USER = {}), Node A: (NAT2, USER = {User A, User C}). The main diagram shows the Internet cloud connected to a 'Bearer network information' box. Below the Internet, there are several NATs and nodes: NAT1 (public IP 202.112.100.100, private IP 10.10.1.*), NAT2 (public IP 10.10.1.100, private IP 192.168.1.*), NAT-U1 (private IP 192.168.1.2), NAT-U2 (private IP 192.168.1.2), NAT3 (public IP 202.112.200.100, private IP 10.10.1.*), NAT-U3 (private IP 10.10.1.101), and NAT-U4 (private IP 10.10.1.102). Nodes are connected as follows: Node D to NAT1; Node A to NAT2; Node C to NAT3; User A to NAT-U1; User C to NAT-U2; Node B to NAT-U4; User D to NAT-U3. Dashed green lines represent bearer network information paths between the Internet cloud and various nodes and NATs.](365b54f616aff249b4e6c0edafdcb9b3_img.jpg)
+
+Diagram illustrating network topology and NAT configurations for a P2P system. At the top, a MOCC entrance connects to a dashed box containing NLRF and RASF. An inset box shows a network topology with Node C, Node D, Node B, and Node A. Node C is connected to Node D and Node B. Node D is connected to Node A. Node B is connected to Node A. Associated with these nodes are state boxes: Node C: (-, USER = {}), Node D: (NAT3, USER = {User D}), Node B: (NAT1, USER = {}), Node A: (NAT2, USER = {User A, User C}). The main diagram shows the Internet cloud connected to a 'Bearer network information' box. Below the Internet, there are several NATs and nodes: NAT1 (public IP 202.112.100.100, private IP 10.10.1.\*), NAT2 (public IP 10.10.1.100, private IP 192.168.1.\*), NAT-U1 (private IP 192.168.1.2), NAT-U2 (private IP 192.168.1.2), NAT3 (public IP 202.112.200.100, private IP 10.10.1.\*), NAT-U3 (private IP 10.10.1.101), and NAT-U4 (private IP 10.10.1.102). Nodes are connected as follows: Node D to NAT1; Node A to NAT2; Node C to NAT3; User A to NAT-U1; User C to NAT-U2; Node B to NAT-U4; User D to NAT-U3. Dashed green lines represent bearer network information paths between the Internet cloud and various nodes and NATs.
+
+**Figure I.8 – The lowest-level NATs are connected and owned by the users**
+
+
+
+
+
+# SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                             |
+|-----------------|---------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                           |
+| Series D        | General tariff principles                                                                   |
+| Series E        | Overall network operation, telephone service, service operation and human factors           |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                             |
+| Series G        | Transmission systems and media, digital systems and networks                                |
+| Series H        | Audiovisual and multimedia systems                                                          |
+| Series I        | Integrated services digital network                                                         |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals |
+| Series K        | Protection against interference                                                             |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant     |
+| Series M        | Telecommunication management, including TMN and network maintenance                         |
+| Series N        | Maintenance: international sound programme and television transmission circuits             |
+| Series O        | Specifications of measuring equipment                                                       |
+| Series P        | Terminals and subjective and objective assessment methods                                   |
+| Series Q        | Switching and signalling                                                                    |
+| Series R        | Telegraph transmission                                                                      |
+| Series S        | Telegraph services terminal equipment                                                       |
+| Series T        | Terminals for telematic services                                                            |
+| Series U        | Telegraph switching                                                                         |
+| Series V        | Data communication over the telephone network                                               |
+| Series X        | Data networks, open system communications and security                                      |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks   |
+| Series Z        | Languages and general software aspects for telecommunication systems                        |

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@@ -0,0 +1,609 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+**F.746.13**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(03/2022)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for smart speaker-based  
+intelligent multimedia communication systems**
+
+Recommendation ITU-T F.746.13
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font superimposed on the globe.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## Recommendation ITU-T F.746.13
+
+# Requirements for smart speaker-based intelligent multimedia communication systems
+
+## Summary
+
+Recommendation ITU-T F.746.13 specifies requirements for intelligent multimedia communication for various types of smart speaker, including those for the reference architecture, smart devices, signalling and platforms, as well as giving a few typical scenario examples. Recommendation ITU-T F.746.13 also specifies requirements for eliminating differences in multimedia communication and access management of heterogeneous devices, to simplify the construction complexity of intelligent multimedia communication systems (IMCSs), to improve the security and reliability of signalling and multimedia data transmission between smart speakers and IMCSs, with a view to finally guaranteeing high-quality multimedia communication service.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.746.13 | 2022-03-16 | 16          | <a href="http://handle.itu.int/11.1002/1000/14960">11.1002/1000/14960</a> |
+
+## Keywords
+
+Intelligent, multimedia communication system, requirements, smart speaker.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2022
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|            |                                                              |    |
+|------------|--------------------------------------------------------------|----|
+| 1          | Scope .....                                                  | 1  |
+| 2          | References.....                                              | 1  |
+| 3          | Definitions .....                                            | 2  |
+| 3.1        | Terms defined elsewhere .....                                | 2  |
+| 3.2        | Terms defined in this Recommendation.....                    | 2  |
+| 4          | Abbreviations and acronyms .....                             | 2  |
+| 5          | Conventions .....                                            | 3  |
+| 6          | Overview of intelligent multimedia communication system..... | 3  |
+| 7          | Smart device requirement .....                               | 4  |
+| 7.1        | Hardware requirement .....                                   | 4  |
+| 7.2        | Software requirements .....                                  | 5  |
+| 7.3        | Artificial intelligent interaction requirement.....          | 6  |
+| 8          | Signalling requirement .....                                 | 7  |
+| 8.1        | Codec requirement.....                                       | 7  |
+| 8.2        | Transmission engine requirement.....                         | 7  |
+| 8.3        | Media streaming requirement.....                             | 7  |
+| 8.4        | Security requirement .....                                   | 7  |
+| 9          | Platform requirement .....                                   | 7  |
+| 9.1        | Communication requirements .....                             | 7  |
+| 9.2        | Application requirement.....                                 | 9  |
+| 9.3        | Operational requirement.....                                 | 9  |
+| Appendix I | – Typical use cases and scenarios.....                       | 11 |
+| I.1        | Family communication.....                                    | 11 |
+| I.2        | Family and community security .....                          | 11 |
+| I.3        | Hotel service.....                                           | 11 |
+|            | Bibliography.....                                            | 12 |
+
+
+
+# **Requirements for smart speaker-based intelligent multimedia communication systems**
+
+# **1 Scope**
+
+This Recommendation specifies requirements for smart speaker-based intelligent multimedia communication systems (IMCSs). This Recommendation describes scenarios and requirements for the entire system to support multimedia communication capabilities over smart devices such as smart speakers.
+
+The scope of this Recommendation includes:
+
+- requirements for smart devices to access IMCSs, including those for multimedia, artificial intelligence (AI) interaction and signalling;
+- requirements for platforms for IMCSs, including those for communications, applications and operations;
+- requirements for security considerations of IMCSs, including those for access control, as well as calling management and transport encryption;
+- typical use cases and application scenarios of IMCSs.
+
+# **2 References**
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T G.711] Recommendation ITU-T G.711 (1988), *Pulse code modulation (PCM) of voice frequencies*.
+- [ITU-T G.722.2] Recommendation ITU-T G.722.2 (2003), *Wideband coding of speech at around 16 kbit/s using adaptive multi-rate wideband (AMR-WB)*.
+- [ITU-T H.264] Recommendation ITU-T H.264 (2021), *Advanced video coding for generic audiovisual services*.
+- [ITU-T H.265] Recommendation ITU-T H.265 (2021), *High efficiency video coding*.
+- [3GPP TS 24.229] 3GPP TS 24.229 V17.6.1 (2022-03), *3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; IP multimedia call control protocol based on session initiation protocol (SIP) and session description protocol (SDP): Stage 3 (Release 17)*.
+- [ETSI EN 301 703] ETSI EN 301 703 V7.0.2 (1999), *Digital cellular telecommunications system (Phase 2+); Adaptive multi-rate (AMR); Speech processing functions; General description (GSM 06.71 Version 7.0.2 Release 1998)*.
+- [IETF RFC 3550] IETF RFC 3550 (2003), *RTP: A transport protocol for real-time applications*.
+- [IETF RFC 4566] IETF RFC 4566 (2006), *SDP: Session description protocol*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 automatic speech recognition (ASR)** [b-ITU-T F.745]: A system that can recognize continuous speech, often having phoneme-sized references, using lexical, syntactic, semantic, and pragmatic knowledge, and reacts appropriately (therefore having interpreted the message and found the corresponding action to be taken). [b-ITU-T P.10]
+
+**3.1.2 smart speaker** [b-ITU-T Y.4204]: A speaker that is capable of anything beyond just emitting sound.
+
+NOTE – Typically, smart speaker refers to an artificial intelligence speaker that utilizes voice recognition technology and is equipped with Internet connectivity.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 intelligent voice interaction:** A technology that is capable of giving appropriate voice feedback according to natural language input by using the speech recognition ability embedded in a terminal or deployed in cloud.
+
+**3.2.2 IP multimedia subsystem:** An architectural framework for delivering multimedia services over the Internet protocol that is specified in [b-ETSI TS 123 228].
+
+**3.2.3 smart display:** A smart speaker with a screen to display multimedia information.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                        |
+|--------|----------------------------------------|
+| AI     | Artificial Intelligence                |
+| AMR    | Adaptive Multi-Rate                    |
+| AMR-WB | Adaptive Multi-Rate Wideband           |
+| ASR    | Automatic Speech Recognition           |
+| BCLK   | Base Clock                             |
+| IMS    | Internet protocol Multimedia Subsystem |
+| ID     | Identifier                             |
+| IP     | Internet Protocol                      |
+| LRCK   | Left Right Channel Clock               |
+| MCLK   | Master Clock                           |
+| MIC    | Microphone                             |
+| NLP    | Natural Language Processing            |
+| PBX    | Private Branch exchange                |
+| PCMA   | Pulse Code Modulation A-law algorithm  |
+| PCMU   | Pulse Code Modulation U-law algorithm  |
+| RTCP   | Real-time Transport Control Protocol   |
+| RTP    | Real-time Transport Protocol           |
+
+|      |                                     |
+|------|-------------------------------------|
+| SDK  | Software Development Kit            |
+| SDP  | Session Description Protocol        |
+| SIP  | Session Initiation Protocol         |
+| SRTP | Secure Real-time Transport Protocol |
+| TV   | Television                          |
+| WLAN | Wireless Local Area Network         |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The phrase "is required to" indicates a requirement that must be strictly followed and from which no deviation is permitted if conformity to this Recommendation is to be claimed.
+- The phrase "is recommended" indicates a requirement that is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformity.
+
+# 6 Overview of intelligent multimedia communication system
+
+Figure 6-1 shows that the system contains an architecture of three layers named: smart device; application; and network. Clauses 7 to 9 provide requirements on three aspects: smart device; multimedia communication platform; and security issues. The network requirement currently lies outside the scope of this Recommendation, it is left for further study. In Appendix I, some typical use cases and scenarios are further described.
+
+The AI interaction module includes:
+
+- AI capabilities for communication purposes;
+- differentiation calling initiation from home automation control;
+- text or voice-based recognition.
+
+![Figure 6-1: Example of intelligent multimedia communication system architecture. The diagram shows three domains: Smart device domain, Application domain, and Network domain. The Smart device domain contains a 'Smart device' box with 'Multimedia processing', 'AI interaction', and 'Signalling processing' modules. It connects via an 'IP access node' to the Application domain. The Application domain contains a 'Multimedia communication service platform' box with 'Operation module', 'Application module', and 'Communication module'. The 'Communication module' connects to the Network domain, which contains 'BOSS' and 'IMS network' boxes. The reference F.746.13(22) is shown at the bottom right.](a234352dfaccdc24745c88eef7724cc6_img.jpg)
+
+Figure 6-1: Example of intelligent multimedia communication system architecture. The diagram shows three domains: Smart device domain, Application domain, and Network domain. The Smart device domain contains a 'Smart device' box with 'Multimedia processing', 'AI interaction', and 'Signalling processing' modules. It connects via an 'IP access node' to the Application domain. The Application domain contains a 'Multimedia communication service platform' box with 'Operation module', 'Application module', and 'Communication module'. The 'Communication module' connects to the Network domain, which contains 'BOSS' and 'IMS network' boxes. The reference F.746.13(22) is shown at the bottom right.
+
+Figure 6-1 – Example of intelligent multimedia communication system architecture
+
+# 7 Smart device requirement
+
+In general, smart speakers are capable of supporting multimedia communication if they meet the hardware, software and AI interaction requirements in clauses 7.1 to 7.3, which are summarized based on observation of large-scale online services.
+
+## 7.1 Hardware requirement
+
+For smart speakers, if the operating system is Linux the following requirements are recommended.
+
+- a) The available space of the flash is required to be larger than 20 Mbyte, and the tool chain e.g., compiler GCC 5.0 or above, is required.
+- b) The compilation environment is required to support C++ version 11.0, and the underlying audio driver is required to support advanced Linux sound architecture.
+
+For smart speakers with an Android operating system, the following requirements are recommended.
+
+- a) Android version 4.2 or above is required.
+- b) The capacity for storing the driver program is recommended to be greater than 9.4 Mbyte.
+- c) The flash capacity is recommended to be more than 67 Mbyte.
+
+### 7.1.1 Requirements of camera and screen for smart display
+
+Table 7-1 lists additional requirements that are recommended for smart display to give a better user experience if multimedia communication is supported.
+
+**Table 7-1 – Additional requirements of smart display**
+
+| Functional blocks |            | Requirements             |
+|-------------------|------------|--------------------------|
+| Pixels of camera  |            | no less than 2 Mpixels   |
+| Display           | resolution | 800 × 480 and above      |
+|                   | size       | not less than 3.9 inches |
+|                   | touch mode | multiple types of touch  |
+
+### 7.1.2 Requirements of wireless local area network interface
+
+The wireless local area network (WLAN) interface is required to comply with IEEE 802.11 a/b/g/n protocol standards, and the interface of WLAN is recommended to support 802.11ax (WiFi6) protocols [b-IEEE 802.11ax] or 802.11ac protocols [b-IEEE 802.11].
+
+The frequency spectrum is required to support 2.4 GHz (according to requirements for mainstream products in the market), and the frequency spectrum is recommended to support 5 GHz.
+
+It is required to support IPv4, IPv6 protocols.
+
+### 7.1.3 Additional requirements
+
+Table 7-2 lists requirements for the speaker and microphone (MIC).
+
+**Table 7-2 – Additional requirements of speaker and microphone**
+
+|         |                         | Smart Speaker without screen                               | Smart display      |
+|---------|-------------------------|------------------------------------------------------------|--------------------|
+| Speaker | Power of single speaker | no less than 2 W                                           | no less than 2 W   |
+|         | Quantity                | no less than one                                           |                    |
+|         | Requirement             | full spectrum                                              |                    |
+| Audio   | Frequency response      | 120-16 kHz (–6 dB)                                         |                    |
+|         | S/N                     | no less than 75 dB                                         | no less than 75 dB |
+| MIC     | Sensitivity             | –26 dBFS @94 dB SPL@ 1 kHz<br>–38 dBV/Pa @94 dB SPL@ 1 kHz |                    |
+|         | S/N                     | no less than 62 dB                                         |                    |
+|         | Material                | silicon microphone                                         |                    |
+|         | Quantity                | no less than two in home or hotel scenarios                |                    |
+
+A list of acoustic requirements for a smart speaker follows.
+
+- a) MIC consistency should be kept within  $\pm 3$  dB.
+- b) The airtightness of the entire MIC is required to meet the requirement that the difference of amplitude frequency response between the blocked case and unblocked case is not less than 15 dB.
+- c) The frequency response of the speaker is about 120-16 kHz.
+- d) The resonant frequency in the high frequency range should be greater than 8 kHz.
+
+Table 3 lists additional requirements of a MIC array.
+
+**Table 7-3 – Additional requirements of microphone array**
+
+| Category                  | Requirements                                                                                                 |
+|---------------------------|--------------------------------------------------------------------------------------------------------------|
+| Instruction & calculation | Floating-point computation                                                                                   |
+|                           | 4 500 Dhrystone million instructions executed per second                                                     |
+| I2S interface             | Left right channel clock (LRCK): 44.1 kHz<br>Base clock (BCLK): 6.144 MHz<br>Master clock (MCLK): 12.288 MHz |
+|                           | Left alignment, most significant bit                                                                         |
+|                           | 16 bits, 32-bit wide                                                                                         |
+|                           | BCLK and MCLK clock synchronization                                                                          |
+|                           |                                                                                                              |
+| I2C interface             | Bit-rate no greater than 100 kbit/s                                                                          |
+|                           | Write operations exceeding 40 bytes                                                                          |
+| RAM occupied              | No more than 50 Mbyte                                                                                        |
+| ROM occupied              | No more than 25 Mbyte                                                                                        |
+| Audio re-sampling         | Support analogue audio data re-sampling                                                                      |
+
+## 7.2 Software requirements
+
+Software requirements can be classified into three categories for: a) the smart speaker side; b) access protocols between smart speakers and the platform; c) adaptation between smart speakers and applications.
+
+The software requirements for smart speaker include those for underlying software design, supporting protocols, operating system, security function and management.
+
+The software requirements of access protocols between smart speaker and platform mainly relate to those for service and management.
+
+In order to support communication with the platform, it is required for smart speakers to be able to pre-set a specific software development kit (SDK). With ready-made capability, services such as terminal management, access control and other security control can be achieved.
+
+Manufacturers are required to have the ability to develop embedded software or firmware for their systems to be able to adapt to the SDK and to upgrade and maintain subsequent versions of the software.
+
+## 7.3 Artificial intelligent interaction requirement
+
+Smart speakers that are capable of supporting multimedia communication are required to support the intelligent interaction requirements, such as voice wake-up and voice recognition, as well as multimedia application interaction requirements, such as quick response and multiple rounds of dialogue (at least two rounds of dialogue and application query).
+
+![Diagram of intelligent interaction process showing the flow from voice input through voice recognition, natural language understanding, AI core module, AI cloud, control command and execution, natural language generation, and speech synthesis to voice output.](d4af765160d04ecef538e5066006dc77_img.jpg)
+
+```
+
+graph LR
+    VI[Voice input] --> VR[Voice recognition]
+    VR --> NLU[Natural language understanding]
+    NLU --> ACM[AI core module]
+    NLU --> AC[AI cloud]
+    AC <--> ACM
+    ACM --> CCE[Control, command and execution, i.e., dialogue, multimedia play]
+    CCE <--> ACM
+    ACM --> NLG[Natural language generation]
+    NLG --> SS[Speech synthesis]
+    SS --> VO[Voice output]
+  
+```
+
+F.746.13(22)
+
+Diagram of intelligent interaction process showing the flow from voice input through voice recognition, natural language understanding, AI core module, AI cloud, control command and execution, natural language generation, and speech synthesis to voice output.
+
+**Figure 7-1 – Diagram of intelligent interaction process**
+
+To support the functions previously listed, the intelligent interaction process is required to include the following modules or to provide similar functions:
+
+- a) voice recognition: converting voice signals into text signals;
+- b) natural language understanding: extracting key information from text signals;
+- c) AI core module: being responsible for dialogue management based on key information or completing the execution of corresponding control commands and generating further feedback information;
+- d) AI cloud: being used to communicate with the AI core module to deal with AI inference tasks;
+- e) natural language generation: generating text signals according to feedback information from the AI core module;
+- f) Speech synthesis: converting text signals into speech signals and generating a synthetic voice.
+
+### 7.3.1 Artificial intelligence-based voice user interaction
+
+A voice trigger that enables users to invoke a speech recognition engine by saying a specific phrase is required.
+
+ASR is required to support basic operation over smart speakers. It is recommended to support far-field ASR [b-Haeb-Umbach] over 3.5 m.
+
+### 7.3.2 Artificial intelligence-based operation interface
+
+In general, key interaction is supported by most smart speakers. Some smart displays can support multitouch interaction on screens. With the development of AI technologies, it is necessary to support multimedia communication over smart devices. For example, natural language processing (NLP) [b-Guida], used to help understand user voice intention, is required to support multimedia interaction in the data corpus. Here, standard language is recommended, and dialect is not compulsory in the first stage.
+
+#### 7.3.3 Artificial intelligence-based assistance tips
+
+Consideration of advanced intelligent interaction services, such as hand gesture recognition and scene detection, is also recommended to provide a better human-computer interaction experience. With the development of more advanced AI technologies, there can be more mechanisms for users.
+
+# 8 Signalling requirement
+
+Signalling requirements of smart speakers that have multimedia communication access capability include those for a codec, transmission engine and media streaming.
+
+## 8.1 Codec requirement
+
+To meet coding and decoding requirements, the following coding and decoding methods, including pulse code modulation A-law algorithm (PCMA) and pulse code modulation U-law algorithm (PCMU) [ITU-T G.711], adaptive multi-rate (AMR) [ETSI EN 301 703] and adaptive multi-rate wideband (AMR-WB) [ITU-T G.722.2] must be supported.
+
+First, to access the Internet protocol (IP) multimedia subsystem (IMS) core network, the corresponding coding methods can be used to complete audio coding, decoding, packaging and disassembling package. Second, support for a variety of video encoding methods, such as VP8 [b-IETF RFC 6386], [ITU-T H.264], [ITU-T H.265] and other video encoding standards, is required. Third, ability to process captured original video in advance to eliminate the effect of ambient light on it is also required. Moreover, adaptation of the code rate to network jitter, delay and packet loss is required to achieve better performance.
+
+## 8.2 Transmission engine requirement
+
+It is necessary to ensure the safety of transmissions. Commonly used methods are:
+
+- a) solving network traversal issues in peer-to-peer transmissions; and
+- b) encryption of audio and video information using SRTP [b-IETF RFC 3711].
+
+## 8.3 Media streaming requirement
+
+For media streaming requirements, support for the real-time transport protocol (RTP) and real-time transport control protocol (RTCP) [IETF RFC 3550] is necessary by smart speakers.
+
+## 8.4 Security requirement
+
+For smart speakers with multimedia communication capability, it is recommended that security requirements include those in clauses 8.1 to 8.3, including encryption of transmission and content. This Recommendation also specifies additional security requirements.
+
+# 9 Platform requirement
+
+## 9.1 Communication requirements
+
+The communication module is required to realize the following functions: registration management; business management; calling database management; monitoring management; call management, media agent and IMS agent.
+
+### 9.1.1 Registration management
+
+The function of registration management is required to support:
+
+- a) allocation of the corresponding phone number according to the pre-allocated unique identifier (ID) for a smart speaker device, such as a mobile equipment identity;
+- b) configuration of different formats of phone number for smart speakers, including but not limited to fixed number or mobile phone number;
+- c) management of multiple types of smart speakers simultaneously, and conversion of signalling according to operators' requirements;
+- d) registration of the corresponding phone number on the IMS for smart speakers, and handling signalling transmission and media stream transmission during a call;
+- e) recording of the registration status of pre-allocated ID and telecommunication number, and other information;
+- f) initiation of signalling such as session initiation protocol (SIP) and SDP ([b-IETF RFC 3261], [3GPP TS 24.229] and [IETF RFC 4566]).
+
+### **9.1.2 Business management**
+
+Deployment of the calling configuration, such as call sequence schedule, simultaneous vibration, sequential vibration and number regulation, should be supported.
+
+### **9.1.3 Calling database management**
+
+The function of calling database management is required to support:
+
+- a) generation of a calling database after each call;
+- b) collection of statistics, billing, verification and other calling-related data functions.
+
+#### **9.1.4 Monitoring management**
+
+The function of monitoring management is required to support:
+
+- a) recording of the operating status of each component in the communication module;
+- b) retrieval, monitoring, alarm and analysis based on the operating status of each component in the communication module.
+
+#### **9.1.5 Signalling controller**
+
+The function of signalling controller is required to:
+
+- a) be supported in the IMS system, for which it should use SIP signalling to realize authentication for smart speakers and servers, signalling routing, session control (simultaneous vibration, sequential vibration, session management and control), media control, multiple device control, and other functions;
+- b) support SIP and SDP according to [3GPP TS 24.229] and [IETF RFC 4566].
+
+#### **9.1.6 Media agent**
+
+The function of media agent is required to support:
+
+- a) establishment of media links between smart speakers and additional functions, including video synthesis, audio mixing, transcoding and data forwarding;
+- b) the following codecs: PCMA/PCMU [ITU-T G.711], AMR [ETSI EN 301 703] and AMR-WB [ITU-T G.722.2];
+- c) the codec in [ITU-T H.264].
+
+#### **9.1.7 Internet protocol multimedia subsystem agent**
+
+The function of an IMS agent is required to support:
+
+- a) the establishment, modification and release of multimedia communication service;
+- b) signalling, receiving and forwarding between the signalling controller and the IMS system;
+- c) signalling conversion and routing;
+- d) signalling interaction using SIP and SDP [3GPP TS 24.229] and [IETF RFC 4566];
+- e) RTP and RTCP [IETF RFC 3550] to support multimedia communication.
+
+## **9.2 Application requirement**
+
+The application module is required to manage: accounts; logins; and calling.
+
+### **9.2.1 Account management**
+
+The function of account management is required to support:
+
+- a) storage of phone numbers, authentication passwords and other account-associated information when the service is activated;
+- b) enquiries of service plan information;
+
+- c) the maintenance and management of smart speaker information, including device serial number and authentication information.
+
+### **9.2.2 Login management**
+
+The function of login management is required to support:
+
+- a) acquisition of configuration information, including business configuration, account information, authentication account number and authentication password during the login procedure;
+- b) synchronously recording of device login operations.
+
+### **9.2.3 Calling management**
+
+The function of call management is required to support:
+
+- a) phone number querying and corresponding name display;
+- b) telephone address list management;
+- c) the maintenance and management of calling rules, including timeout, calling transfer and calling sequence.
+
+## **9.3 Operational requirement**
+
+The operation module is required to realize the following functions: platform configuration; business configuration; operation and maintenance management.
+
+### **9.3.1 Platform configuration**
+
+The function of platform configuration is required to support:
+
+- a) software management of the platform, including service registration and discovery, configuration centre, service gateway, and service degradation;
+- b) the configuration of hardware equipment, including load balancing and message clustering.
+
+### **9.3.2 Business configuration**
+
+The function of business configuration is required to support:
+
+- a) service configuration, including account type, authentication method, account data verification, data synchronization, and some others;
+- b) configuration of calling rules, white list for controlling users and other daily operational management.
+
+### **9.3.3 Operation and maintenance management**
+
+Several operation and maintenance functions, including containerized automatic deployment, resource status monitoring, log monitoring management and real-time service alarms should be supported.
+
+# Appendix I
+
+## Typical use cases and scenarios
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The typical IMCS has been deployed by China Mobile with AI-based multimedia calls (AICall), which has now served 5.6 million registered users all over China. The activity ratio of AICall has improved by over 200% when compared to that of legacy fixed lines.
+
+### I.1 Family communication
+
+The smart speaker-based multimedia communication service can be used in family communication scenarios to satisfy a variety of communication demands, such as realizing high-quality audio or video communication on multiform devices with different scene sizes.
+
+It is convenient that the embedded AI speech recognition function helps people realize different interactions, such as intelligent voice interaction, keyless operation as well as wake-up and calling anyone in the family. When people use voice over long-term evolution to call these multiform devices at home, all devices, including television (TV), with smart displays respond with video or audio calls subsequently or simultaneously. People can answer calls on TV to experience the high definition and immersive calling service or directly on smart speakers for easy usage.
+
+### I.2 Family and community security
+
+For traditional communities, demands on the ability of audio or video communication are getting urgent for common surveillance devices, such as home pads and peephole video doorbells. A variety of multiform smart devices can easily enjoy services via remote internal upgrade with a specific SDK.
+
+Existing smart devices, such as TVs, speakers and phones, can be used to link with home pads and peephole doorbells to provide high-quality video calls and other interactive services.
+
+### I.3 Hotel service
+
+The smart speaker-based multimedia services are suitable for smart hotel scenarios. Use of multiform smart terminals integrated with IMS, cloud private branch exchange (PBX) and AI technologies, can provide users with intelligent customer service, information queries and other special services.
+
+Various smart terminals in hotel rooms can be used to make cross-network and cross-domain calls with the help of intelligent voice interaction. In addition, users can also contact the hotel reception via these smart terminals as well as to receiving some specific services such as wake-up calls, renewal confirmation, cleaning, maintenance and meal delivery.
+
+# Bibliography
+
+- [b-ITU-T F.745] Recommendation ITU-T F.745 (2016), *Functional requirements for network-based speech-to-speech translation services*.
+- [b-ITU-T P.10] Recommendation ITU-T P.10/G.100 (2017), *Vocabulary for performance, quality of service and quality of experience*.
+- [b-ITU-T Y.4204] Recommendation ITU-T Y.4204 (2019), *Accessibility requirements for the Internet of things applications and services*.
+- [b-ETSI TS 123 228] Technical Specification ETSI TS 123 228 V17.3.0 (2022), *Digital cellular telecommunications system (Phase 2+) (GSM);Universal Mobile Telecommunications System (UMTS);LTE; IP Multimedia Subsystem (IMS);Stage 2 (3GPP TS 23.228 version 17.3.0 Release 17)*.
+- [b-IEEE 802.11] IEEE 802.11-2016,<sup>1</sup> *IEEE Standard for Information technology – Telecommunications and information exchange between systems Local and metropolitan area networks – Specific requirements – Part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications*.
+- [b-IEEE 802.11ax] IEEE 8802.11ax-2021, *IEEE Standard for Information Technology – Telecommunications and information exchange between systems Local and metropolitan area networks – Specific Requirements – Part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications Amendment 1: Enhancements for high-efficiency WLAN*.
+- [b-IETF RFC 3261] IETF RFC 3261 (2002), *SIP: Session initiation protocol*.
+- [b-IETF RFC 3711] IETF RFC 3711 (2004), *The secure real-time transport protocol (SRTP)*.
+- [b-IETF RFC 6386] IETF RFC 6386 (2011), *VP8 data format and decoding guide*.
+- [b-Guida] Guida, G., Mauri, G. (1986). Evaluation of natural language processing systems: Issues and approaches. *Proc. IEEE*. **74** (7), pp. 1026-1035.
+- [b-Haeb-Umbach] Haeb-Umbach, R., Heymann, J., Drude, L., Watanabe, S., Delcroix, M., Nakatani, T. (2021). Far-field automatic speech recognition. *Proc. IEEE*. **109**(2), pp. 124-148.
+
+---
+
+<sup>1</sup> Superseded.
+
+
+
+
+
+## **SERIES OF ITU-T RECOMMENDATIONS**
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,559 @@
+
+
+# Recommendation **ITU-T F.746.14 (12/2022)**
+
+SERIES F: Non-telephone telecommunication services  
+Multimedia services
+
+---
+
+## **Requirements and reference framework for cloud virtual reality systems**
+
+![ITU logo](390120de4fe440c42fea8154fcaad334_img.jpg)
+
+The logo of the International Telecommunication Union (ITU), featuring the letters 'ITU' in blue inside a circle with a globe-like grid pattern.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS NON-TELEPHONE TELECOMMUNICATION SERVICES
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| MOBILE SERVICE                                                  |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| TELEMATIC SERVICES                                              |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400–F.499        |
+| DIRECTORY SERVICES                                              | F.500–F.549        |
+| DOCUMENT COMMUNICATION                                          |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| ISDN SERVICES                                                   | F.800–F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850–F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.746.14
+
+## Requirements and reference framework for cloud virtual reality systems
+
+## Summary
+
+Cloud virtual reality based on cloud capabilities, can effectively shield terminal differences, reduce the difficulty of application development, lower some specific industry entry barriers, and promote the industry business chain cooperation.
+
+Recommendation ITU-T F.746.14 focuses on the overall requirements of cloud virtual reality systems and the related requirements of each layer including content requirements, network requirements, control requirements, resource requirements and terminal requirements, as well as the reference framework for related high-level functions.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.746.14 | 2022-12-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/15188">11.1002/1000/15188</a> |
+
+## Keywords
+
+Cloud virtual reality, reference framework, requirements, virtual reality.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                      | Page |
+|------------------------------------------------------|------|
+| 1 Scope .....                                        | 1    |
+| 2 References.....                                    | 1    |
+| 3 Definitions .....                                  | 1    |
+| 3.1 Terms defined elsewhere .....                    | 1    |
+| 3.2 Terms defined in this Recommendation.....        | 1    |
+| 4 Abbreviations and acronyms .....                   | 1    |
+| 5 Conventions .....                                  | 2    |
+| 6 Overview .....                                     | 2    |
+| 7 Reference framework of cloud VR systems .....      | 3    |
+| 8 Requirements of cloud virtual reality systems..... | 4    |
+| 8.1 General requirements.....                        | 4    |
+| 8.2 Content layer .....                              | 5    |
+| 8.3 Control layer.....                               | 5    |
+| 8.4 Resource layer .....                             | 6    |
+| 8.5 Terminals.....                                   | 6    |
+| 8.6 Network.....                                     | 7    |
+| 8.7 Operation, administration and management.....    | 8    |
+| 8.8 Security.....                                    | 8    |
+| Appendix I – Use cases.....                          | 9    |
+| I.1 Cloud VR game .....                              | 9    |
+| I.2 Cloud VR live broadcast .....                    | 10   |
+| I.3 Cloud VR education .....                         | 11   |
+| Bibliography.....                                    | 13   |
+
+
+
+# Recommendation ITU-T F.746.14
+
+## Requirements and reference framework for cloud virtual reality systems
+
+# 1 Scope
+
+This Recommendation specifies the requirements and reference framework for cloud virtual reality systems.
+
+The scope of this Recommendation includes:
+
+- 1) overview of cloud virtual reality systems;
+- 2) reference framework for cloud virtual reality systems;
+- 3) requirements for cloud virtual reality systems.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T J.1631] Recommendation ITU-T J.1631 (2021), *Functional requirements of E2E network platforms to enhance the delivery of cloud-VR services over integrated broadband cable networks*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 degree of freedom (DoF)** [b-ITU-T G.1035]: Represents the ways an object can move within a space, which is a key element in helping create an immersive environment for a user.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 operations latency:** The time it takes for the entire process from the terminal issuing a control command to the application content responding to the operation request and completing output.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                                        |
+|-----|----------------------------------------|
+| 2D  | Two Dimensions                         |
+| 3D  | Three Dimensions                       |
+| 3I  | Immersion, Interaction and Imagination |
+| API | Application Programming Interface      |
+| ARM | Application Resource Manager           |
+
+|          |                                          |
+|----------|------------------------------------------|
+| ATW      | Asynchronous Time Warp                   |
+| CDN      | Content Delivery Network                 |
+| Cloud VR | Cloud Virtual Reality                    |
+| CPU      | Central Processing Unit                  |
+| 3DoF     | Three Degrees of Freedom                 |
+| E2E      | End-to-End                               |
+| FOV      | Field of View                            |
+| FTTH     | Fibre To The Home                        |
+| GPU      | Graphic Processing Unit                  |
+| HMD      | Head-mounted Display                     |
+| OAM      | Operation, Administration and Management |
+| QoE      | Quality of Experience                    |
+| SDK      | Software Development Kit                 |
+| VR       | Virtual Reality                          |
+| WDM      | Wavelength Division Multiplexing         |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+- The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+# 6 Overview
+
+Cloud virtual reality (cloud VR) is a new method for providing service of virtual reality based on cloud capabilities, which comprehensively uses cloud computing, rendering, audio and video processing and other multimedia technologies. Cloud VR continues and enhances VR related immersion, interaction and imagination (3I) attributes.
+
+Cloud VR has a processing method based on cloud unified content storage and cloud logical computing, which is different from VR terminal mode that finishes logic computing, graphics rendering, and content storage by VR terminals. For the implementation of cloud VR, there are several ways used for graphics rendering, and audio and video processing, such as cloud and terminal collaboration, and terminal alone.
+
+There are many kinds of cloud VR application scenarios, which have different classifications.
+
+- From the industry dimension, cloud VR application scenarios are divided into personal consumption-level scenarios and enterprise-level scenarios. Personal consumption-level scenarios include video-on-demand, live broadcast, games, social networking, education and other analogous fields. Enterprise-level scenarios include military, medical, construction, industrial manufacturing and other analogous fields.
+- From the interaction dimension, cloud VR application scenarios are divided into weak interaction scenarios and strong interaction scenarios. Weak interaction scenarios are mainly VR video services, including VR videos, and VR live broadcasts. Strong interactive
+
+scenarios usually involve cloud real-time rendering, and interaction with virtual environments or objects, including VR games, VR education, VR fitness, VR social and VR industrial manufacturing.
+
+Two level services and two types of interaction services need different service, network and terminal capabilities, and service logic processing in cloud VR.
+
+Use cases of the cloud VR services are discussed in Appendix I.
+
+# 7 Reference framework of cloud VR systems
+
+Figure 7-1 shows the reference framework for cloud VR systems. The cloud VR systems implement cloud-based operations through various types of application contents and through various services at the resource layer supported by the control layer, and delivers cloud VR contents to different types of terminals through the network to complete the entire service process.
+
+![Figure 7-1: Reference framework for cloud VR systems. The diagram shows a five-layer architecture: Content layer (Games, Videos, Cartoons, Music, ...), Control layer (Technology integration, Content distribution), Resource layer (Cloud resources), Network layer, and Terminal layer (PC VR HMD, Integrated VR HMD, Split VR HMD, ...). Security is on the left, and Cloud VR OA&M is on the right. F.746.14(22) is noted at the bottom right.](367926125450c2bc3f4bdca9d59a62ba_img.jpg)
+
+The diagram illustrates the reference framework for cloud VR systems. It consists of five horizontal layers stacked vertically, flanked by two vertical bars. The left bar is labeled 'Security'. The right bar is labeled 'Cloud VR OA&M'. The layers are: 1. Content layer: contains 'Games', 'Videos', 'Cartoons', 'Music', and '...'. 2. Control layer: contains 'Technology integration' and 'Content distribution'. 3. Resource layer: contains 'Cloud resources'. 4. Network layer: a single empty box. 5. Terminal layer: contains 'PC VR HMD', 'Integrated VR HMD', 'Split VR HMD', and '...'. At the bottom right of the diagram, the text 'F.746.14(22)' is present.
+
+Figure 7-1: Reference framework for cloud VR systems. The diagram shows a five-layer architecture: Content layer (Games, Videos, Cartoons, Music, ...), Control layer (Technology integration, Content distribution), Resource layer (Cloud resources), Network layer, and Terminal layer (PC VR HMD, Integrated VR HMD, Split VR HMD, ...). Security is on the left, and Cloud VR OA&M is on the right. F.746.14(22) is noted at the bottom right.
+
+**Figure 7-1 – Reference framework for cloud VR systems**
+
+The content layer provides various types of application content, including cloud VR games, cloud VR videos, cloud VR cartoons and cloud VR music. According to the industry application perspective, the content of the cloud VR system can divide into cloud VR education, cloud VR fitness, cloud VR social, cloud VR industrial manufacturing, etc.
+
+The control layer provides cloud VR-related capabilities, including technology integration and content distribution:
+
+- The cloud VR technology integration provides audio and video encoding, transcoding, graphics rendering, streaming issuance, control response, and other specified service capabilities for weak and strong interaction services using general cloud resource pool capabilities.
+- The cloud VR content distribution provides distribution of processed cloud VR content from a cloud resource to a corresponding cloud VR user/terminal.
+
+The resource layer provides general hardware computing resources such as central processing units (CPUs) and graphic processing units (GPUs) for cloud VR, and basic software capabilities such as virtual machines, containers or application virtualization.
+
+The network layer provides the communication capabilities for other layers, operation, administration and management (OAM), the users and providers.
+
+The terminal layer receive/send cloud VR related data from/to the cloud, performs partial local processing/computing, and displays the cloud VR content based on the support of software and hardware. There are mainly three types of terminals for cloud VR systems, including PC VR head-mounted display (HMD), integrated VR HMD and split VR HMD:
+
+- PC VR HMD provides basic VR related device capabilities that include display, manipulation, sensing and other capabilities, but has no computing capability for complex media and service logic processing which is provided by PCs or proprietary game consoles.
+- Integrated VR HMD provides all VR related device capabilities that include basic capabilities and computing capability.
+- Split VR device provides basic VR related device capabilities, but has no computing capability which is provided by mobile terminals, such as mobile phones.
+
+The cloud VR OAM provides centralized operating, management and maintenance functions in terms of content, technology integration, and terminals, including user authentication, content introduction, cloud VR technical capability access, and cloud VR terminal management.
+
+Cloud VR provides multi-dimensional security mechanisms, such as the securities of cloud operation, service, data and user experience.
+
+# **8 Requirements of cloud virtual reality systems**
+
+### **8.1 General requirements**
+
+#### **8.1.1 Audio-visual**
+
+The overall audio-visual quality of the cloud VR systems is closely related to the content image/sound quality, computing/coding capabilities, network transmission quality, and terminal secondary processing/display capabilities. It is based on the final presentation of the user's image, sound and interaction requirements.
+
+AV-01: It is recommended to have three-dimensional properties, and its presentation method is not limited to true three dimensions (3D) display or two dimensions (2D) picture synthesis 3D, etc.
+
+AV-02: The image quality is required to reference standard [ITU-T J.1631] FEP related requirements.
+
+AV-03: It is recommended to meet the same refresh rate of the cloud VR terminal's display.
+
+#### **8.1.2 Interaction**
+
+IA-01: It is required to have smooth human-computer interaction.
+
+IA-02: It is required to have acceptable operations latency. In general, the terminal side collects control instructions and uploads them to the cloud through the network, and then the cloud completes the processing and sends the relevant results to the terminal through the network, and finally the terminal side completes the process of corresponding content and output results.
+
+IA-03: It is required to meet three degrees of freedom (3DoF) capability, and support at least one common control method, such as handle, joystick, gesture and voice.
+
+#### **8.1.3 Compatibility**
+
+CB-01: It is required to be compatible with general cloud computing resource pools.
+
+CB-02: It is required to be compatible with various cloud VR technology solutions.
+
+CB-03: It is required to support various VR contents, such as cloud VR content released on the Steam online game platform.
+
+CB-04: It is required to be compatible with network access methods that meet the transmission conditions.
+
+CB-05: It is required to be compatible with various types and different brands of VR terminals that meet the capability requirements.
+
+### **8.2 Content layer**
+
+The quality of cloud VR content is directly related to cloud VR 3I properties. The requirements for cloud VR content are as follows:
+
+CT-01: The content is required to transplant to the cloud and run based on the cloud.
+
+CT-02: It is recommended to have a flexible output method, which can be switched between panoramic and field of view (FOV) modes.
+
+## **8.3 Control layer**
+
+#### **8.3.1 The common requirements of the control layer**
+
+CP-01: The deployment server is required to support general cloud resource pool forms such as physical machines and virtual machines.
+
+CP-02: It is required to support system recovery after software and hardware failures, including data backup/recovery and service node switching. The main types of server failures include plugging and unplugging hard disks, network disconnection, shutdown and restarting.
+
+- With the cooperation of hardware and software, it is required to provide the ability to manage system failures.
+- The design life is required to be greater than 10 years.
+- The fault is required to be isolated in the module (e.g., the service node, etc.).
+- The overall service capability is required to have 7\*24 hours stable operation performance and 99.9% availability.
+- The downtime for failures is required to not exceed 2 hours within three months.
+- Short-term failures of related servers and other equipment are required to not cause alarms and service data.
+
+CP-03: It is required to have flexible scalability to support the seamless addition of service nodes and the operation of servers in the nodes as the service carrying requirements increase, so as to improve the carrying capacity.
+
+CP-04: Compatibility requirements:
+
+- It is required to have the ability to be compatible with the software version. When the software version is upgraded or revised, it has the ability to be compatible with the cloud VR application content previously based on it.
+- It is required to have the ability to be compatible with application content developed based on the general VR framework.
+
+#### **8.3.2 Technology integration**
+
+TI-01: It is required to build cloud VR technical services based on the cloud resource pool.
+
+TI-02: It is required to build cloud VR technology services nodes based on edge nodes.
+
+TI-03: It is recommended to have the ability of GPU-based video encoding.
+
+TI-04: It is required to have the functions such as seamless migration of services and data security assurance.
+
+TI-05: It is required to have the ability to interface with the cloud VR operation services to provide cloud VR technical integration services.
+
+TI-06: It is required to have functions such as docking with cloud VR terminals, obtaining control instructions, and calling audio and video decoding capabilities.
+
+TI-07: For VR weak interactive services, it is required to provide functions such as cloud transcoding, content distribution and content delivery network (CDN) resource scheduling.
+
+TI-08: For VR strong interactive services, it is required to provide at least one method based on virtual machines, containers, and application virtualization to build parallel cloud VR instances:
+
+- It is required to support cloud-based drivers, including rendering driver, video low-latency compression coding and video streaming transmission.
+- Each cloud rendering server or virtual machine is required to have the capability of multi-application rendering parallelism. For rendering services that can run/stream processing with single-core CPU and single-core GPU, it has the parallel operation capability of the smallest cores between CPU and GPU.
+- It is required to achieve a one-to-one correspondence between the number of picture frames and the corresponding picture sound data collection, and the time difference is recommended to not exceed 100 ms.
+
+#### 8.3.3 Content distribution
+
+Cloud VR content distribution has an interface with cloud VR operation, which provides cloud VR content aggregation, recommendation and distribution functions.
+
+CD-01: It is required to provide an effective cloud VR content download or online operation path.
+
+CD-02: It is required to provide a CDN function for cloud VR video service.
+
+CD-03: It is required to provide storage capabilities that match the distribution of cloud VR content.
+
+## 8.4 Resource layer
+
+CR-01: It is required to provide generic physical or virtual CPU, GPU, storage, network card and other hardware resources.
+
+- It is required to provide generic software systems, including safe operating systems, hardware drivers and general graphics interfaces.
+- It is required to provide compliant virtual machines, containers or application virtualizations and other concurrent reuse mechanisms of software and hardware resources.
+
+CR-02: It is required to provide general cloud resource pool configuration, expansion, migration, management and other functions.
+
+CR-03: It is required to provide data storage, and data backup.
+
+CR-04: It is required to provide secure and reliable virtual machines, containers or application virtualizations, one-click migration, and a secure data synchronization mechanism.
+
+## 8.5 Terminals
+
+#### 8.5.1 Hardware
+
+HW-01: It is required to use general CPU architecture such as X86, ARM and others, with complete computing, rendering, storage and other processing capabilities for cloud VR service.
+
+HW-02: It is required to have enough calculation ability, including CPU and GPU.
+
+HW-03: It is required to have enough storage capacity.
+
+HW-04: It is required to provide 2K or more, dual-screen near-eye display capability.
+
+HW-05: It is required to provide 3DOF capability, and is recommended to provide the above 3DOF capability.
+
+HW-06: It is required to provide one or more effective control devices, including handles and VR helmet buttons.
+
+HW-07: It is recommended to provide relevant optical equipment for accurate spatial positioning.
+
+HW-08: It is required to have network access capability above 100 M.
+
+#### **8.5.2 Software**
+
+SW-01: It is recommended to use common operating systems such as Windows, Linux, Android and Harmony.
+
+SW-02: It is required to install hardware drivers.
+
+SW-03: It is required to have the ability to access the different cloud VR layers.
+
+- It is required to support cloud VR user management, authentication, and charging functions through connecting with the different cloud VR layers.
+- It is required to support functions such as receiving cloud VR service audio and video streams and uploading control commands.
+- It is required to support cloud VR content push, update and release functions through connecting with the different cloud VR layers.
+
+SW-04: It is recommended to support multiple codecs, such as H.264, H.265, AVI, and VP9, and also support two or more at the same time.
+
+SW-05: It is required to support the function of a near-eye 3D display.
+
+SW-06: The overall terminal operation delay and processing delay are recommended to be less than 40 ms, of which the asynchronous time warp (ATW) is required to be less than 20 ms, and the graphics and audio data decoding is recommended to be less than 20 ms.
+
+### **8.6 Network**
+
+CN-01: The bandwidth is required to reference standard [ITU-T J.1631] FEP related requirements.
+
+CN-02: The latency is required to be less than or equal to 100 ms. For strong-interaction VR service, it is recommended that the manipulation latency is less than or equal to 50 ms.
+
+CN-03: The packet loss rate is required to less than or equal to  $10^{-4}$  ([ITU-T J.1631] FEP). For strong-interaction VR service, the packet loss rate is recommended to be less than or equal to  $10^{-5}$ .
+
+CN-04: For wired access, it is recommended to use fibre to the home (FTTH) access technology.
+
+CN-05: For wireless cellular access, it is recommended to use 5G and above network access standards.
+
+CN-06: Access delay is required to be less than or equal to 5 ms, and is recommended to be less than or equal to 2 ms.
+
+CN-07: It is recommended to support deterministic network access guarantees for cloud VR services such as bandwidth and delay.
+
+CN-08: It is recommended to provide network guarantee mechanisms such as link path selection and network acceleration.
+
+CN-09: It is recommended to use optical fibre or wavelength division multiplexing (WDM) direct connection between cloud VR edge computing nodes to reduce the delay of multi-person remote interaction.
+
+CN-10: Inside the cloud data centre, a 1 Gbit/s or more network interconnection is required, and 10 Gbit/s or more is recommended.
+
+## **8.7 Operation, administration and management**
+
+CO-01: It is required to have the ability to provide cloud VR operation and management based on a cloud basic resource pool or general server.
+
+CO-02: It is required to have the ability to centralize the management and scheduling of resources in the underlying cloud resource pool.
+
+CO-03: It is required to have the ability to interface with various VR applications, including the ability to import and release VR applications.
+
+CO-04: It is required to have the ability to connect the cloud VR technology integration service.
+
+CO-05: It is required to have service authentication and service invocation/removal capabilities of different cloud VR technical integration services.
+
+CO-06: It is required to have complete user authentication, service billing, data analysis, operation and maintenance, etc.
+
+CO-07: It is required to have the ability to interface with cloud VR terminals, complete user authentication, content synchronization, and charging functions.
+
+CO-08: It is recommended to adopt software development kit (SDK), application programming interface (API) and other forms to provide the capability of a built-in cloud VR terminal for operational capability.
+
+## **8.8 Security**
+
+SR-01: It is required to have the ability to divide security domains according to service nodes, deploy firewalls, intrusion detection, abnormal traffic detection and filtering and other measures.
+
+SR-02: It is required to have anti-virus capabilities and process (logical) security assurance, including access rights restrictions, security audits and other functions.
+
+SR-03: It is required to have the ability to ensure the service security through user management, authority management, log management, etc.
+
+SR-04: It is required to have security protection capabilities for metadata, user access data, business operation data, etc., and use encryption technology to encrypt important data transmitted on the Internet.
+
+SR-05: It is required to have corresponding measures to prevent and deal with simulator sickness, including fatigue, sweating, vertigo and nausea.
+
+## Appendix I
+
+### Use cases
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Through cloud computing, compared with the VR terminal mode, cloud VR has the advantages of enhanced service capability, reduced terminal operation pressure and centralized distribution of content, so as to deduce a variety of rich and colourful use case types.
+
+In order to show the characteristics of cloud VR strong interaction scenarios and cloud VR weak interaction scenarios, this appendix selects typical use cases such as cloud VR games and cloud VR live broadcasts. At the same time, cloud VR education with strong and weak interaction attributes is selected as a typical use case.
+
+Cloud VR game and cloud VR live broadcast serve as as personal consumption-level service representatives, while cloud VR education serves as as an enterprise-level service representative.
+
+### I.1 Cloud VR game
+
+Figure I.1 shows a schematic diagram of cloud VR game. A cloud VR game is a typical use case of cloud VR due to its smooth control experience and multi-person real-time interaction mechanism. Unlike cloud VR video that can use the terminal, CDN and other caching mechanisms to alleviate the experience of problems caused by network instability, cloud VR game needs to complete the transmission of high-capacity media streams and remote control commands from the cloud to the terminal in real time and efficiently.
+
+In terms of content, game content providers are required to inject panoramic game content with exquisite visual effects such as stereoscopic high-definition pictures, etc. In terms of platforms, high-end GPU cluster servers are required to provide functions such as game running, graphics rendering, and audio and video capture/encoding. In the network related to cloud VR game, it is necessary to provide high-bandwidth, low-latency, and low-packet-loss stable data transmission services. In terms of the terminal, it is necessary to accept high-definition graphics data issued by the cloud, and collect corresponding operating instructions data and upload it to the cloud to complete the overall business service process.
+
+![Schematic diagram of cloud VR game architecture showing three layers: content, platform, and terminal.](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+The diagram illustrates the architecture of a cloud VR game, organized into three horizontal layers:
+
+- The content of Cloud VR game:** At the top, a rectangular box contains "Game1 Game 2 ... Game n". A blue line descends from this box to the central management system.
+- The platform of Cloud VR game:** This layer consists of a central cloud labeled "Central management system" connected to three edge nodes labeled "Edge node 1", "Edge node 2", and "Edge node n" (with an ellipsis between nodes 2 and n). Below these nodes is a large cloud labeled "Network transmission guarantee such as high bandwidth, low delay and low packet loss".
+- The terminal of Cloud VR game:** At the bottom, three VR headsets are shown, labeled "VR terminal 1", "VR terminal 2", and "VR terminal n" (with an ellipsis between terminals 2 and n). Blue lines labeled "Network transmission" connect the large network transmission cloud to each VR terminal.
+
+F.746.14(22)
+
+Schematic diagram of cloud VR game architecture showing three layers: content, platform, and terminal.
+
+**Figure I.1 – Schematic diagram of cloud VR game**
+
+Cloud VR game requires high-end GPU servers as the foundation for cloud operations. Through mechanisms such as virtual machines and containers, a server has the ability to carry multiple services. This mechanism has the problem of multiple users repeatedly processing common game graphics data resources, and it also puts pressure on the overall carrying capacity of the cloud. In order to solve the above problems, it is necessary to adopt technological innovations such as multi-user cloud computing resources and multi-dimensional sharing of cloud data resources to avoid the waste of multi-processing of general game graphics.
+
+### I.2 Cloud VR live broadcast
+
+Figure I.2 shows a schematic diagram of cloud VR live broadcast. Cloud VR live broadcast, firstly uses VR technology to achieve panoramic view shooting and surround-sound capture of content. It then uses high-performance servers at the edge nodes close to the live broadcast site to complete the stitching and optimization of audio and video streams. Then through the CDN system, with the help of ultra-high bandwidth's network it realizes multi-user-oriented audio and video distribution. The end user completes the online viewing of the corresponding live broadcast through the VR terminal.
+
+![Schematic diagram of cloud VR live broadcast showing the flow from multiple VR live broadcasts through edge stitching optimization, a CDN platform, and network transmission to multiple VR terminals.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+The diagram illustrates the architecture of a cloud VR live broadcast system. At the top, a box contains "VR live broadcast 1 VR live broadcast 2 ... VR live broadcast n", labeled "The content of Cloud VR live broadcast". This content flows into a cloud labeled "Edge stitching optimization", which is part of "The platform of Cloud VR live broadcast". Below this is a "CDN" cloud. The platform connects to a large cloud labeled "Network transmission guarantee such as high bandwidth". From this cloud, multiple lines labeled "Network transmission" lead to VR terminals labeled "VR terminal 1", "VR terminal 2", "...", and "VR terminal n", collectively labeled "The terminal of Cloud VR live broadcast". A small code "F.746.14(22)" is visible near the bottom right.
+
+Schematic diagram of cloud VR live broadcast showing the flow from multiple VR live broadcasts through edge stitching optimization, a CDN platform, and network transmission to multiple VR terminals.
+
+**Figure I.2 – Schematic diagram of cloud VR live broadcast**
+
+Cloud VR live broadcast is one of the more complex cloud VR video applications. However, because of its online viewing mode, the interaction process only reflects operations such as switching of the focus range and viewing of digital information, and does not involve more complex real-time interaction and so it belongs to cloud VR weak interaction scenarios. At the same time, during the video watching process, modes such as CDN and VR terminal caching can be used to reduce the impact of live broadcast effects caused by network fluctuations, and at the same time reduce the burden of low network latency. If a corresponding virtual image is added to the cloud VR live screen and a real-time interaction mechanism is provided, its attribute is not only a video viewing mode, but a video plus real-time animation interaction mode, which also requires lower network latency.
+
+### I.3 Cloud VR education
+
+Figure I.3 shows a schematic diagram of cloud VR education. Cloud VR education is an application of the cloud VR industry. Online distance education is carried out through cloud VR technology, which has attributes such as intuition, fun and fairness. Especially for countries and regions with uneven distribution of educational resources, the cloud VR education method can concentrate high-quality educational resources to provide more school students with the same quality of teaching services, and promote overall education equity.
+
+Cloud VR education has two mutually integrated service modes. One is the mode of directly playing VR education videos online, which belongs to the cloud VR weak interactive service; the other is panoramic simulation education, where the cloud presents a dynamic virtual image based
+
+on the educational content and provides real-time interactive functions which belong to the cloud VR strong interactive service.
+
+![Schematic diagram of cloud VR education showing the flow from content providers through a central management system, edge nodes, and a network transmission layer to multiple VR terminals.](ff7ce44f3fdd51bae7b231f34df07c6a_img.jpg)
+
+The diagram illustrates the architecture of cloud VR education. At the top, two rectangular boxes represent the content sources: "Cloud VR panoramic simulation education" and "Cloud VR education video". These are connected by lines to a central cloud labeled "Central management system". Above this connection is the label "The content of Cloud VR education".
+
+The "Central management system" is connected to a row of edge nodes: "Edge node 1", "Edge node 2", an ellipsis, and "Edge node n". To the right of "Edge node n" is a "CDN" (Content Delivery Network) represented by two clouds. This entire layer is labeled "The platform of Cloud VR education".
+
+Below the edge nodes is a large horizontal oval representing the "Network transmission" layer, with the text "Network transmission guarantee such as high bandwidth, low delay and low packet loss" inside. This layer is connected to the edge nodes above and to the VR terminals below.
+
+At the bottom, three VR terminal icons are shown, labeled "VR terminal 1", "VR terminal 2", an ellipsis, and "VR terminal n". These are connected to the network transmission layer. Below them is the label "The terminal of Cloud VR education".
+
+F.746.14(22)
+
+Schematic diagram of cloud VR education showing the flow from content providers through a central management system, edge nodes, and a network transmission layer to multiple VR terminals.
+
+**Figure I.3 – Schematic diagram of cloud VR education**
+
+In most cloud VR education scenarios, the above two methods exist at the same time, so cloud VR also has the attributes of strong and weak interaction at the same time. For cloud VR education-related technical details, implementation processes, and functional composition, further analysis and clarification of recommendations are needed.
+
+## Bibliography
+
+- [b-ITU-T G.1035] Recommendation ITU-T G.1035 (2021), *Influencing factors on quality of experience for virtual reality services*.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+# Recommendation **ITU-T F.746.15 (12/2022)**
+
+SERIES F: Non-telephone telecommunication services  
+Multimedia services
+
+---
+
+## **Requirements for smart broadband network gateway in multimedia content transmission**
+
+![ITU logo](390120de4fe440c42fea8154fcaad334_img.jpg)
+
+The logo of the International Telecommunication Union (ITU), featuring the letters 'ITU' in blue inside a circle with a globe-like grid pattern.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+### **TELEGRAPH SERVICE**
+
+|                                                                 |             |
+|-----------------------------------------------------------------|-------------|
+| Operating methods for the international public telegram service | F.1–F.19    |
+| The gentex network                                              | F.20–F.29   |
+| Message switching                                               | F.30–F.39   |
+| The international telemessage service                           | F.40–F.58   |
+| The international telex service                                 | F.59–F.89   |
+| Statistics and publications on international telegraph services | F.90–F.99   |
+| Scheduled and leased communication services                     | F.100–F.104 |
+| Phototelegraph service                                          | F.105–F.109 |
+
+### **MOBILE SERVICE**
+
+|                                                        |             |
+|--------------------------------------------------------|-------------|
+| Mobile services and multdestination satellite services | F.110–F.159 |
+|--------------------------------------------------------|-------------|
+
+### **TELEMATIC SERVICES**
+
+|                                           |             |
+|-------------------------------------------|-------------|
+| Public facsimile service                  | F.160–F.199 |
+| Teletex service                           | F.200–F.299 |
+| Videotex service                          | F.300–F.349 |
+| General provisions for telematic services | F.350–F.399 |
+
+### **MESSAGE HANDLING SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.400–F.499 |
+|--|-------------|
+
+### **DIRECTORY SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.500–F.549 |
+|--|-------------|
+
+### **DOCUMENT COMMUNICATION**
+
+|                                      |             |
+|--------------------------------------|-------------|
+| Document communication               | F.550–F.579 |
+| Programming communication interfaces | F.580–F.599 |
+
+### **DATA TRANSMISSION SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.600–F.699 |
+|--|-------------|
+
+### **MULTIMEDIA SERVICES**
+
+|  |                    |
+|--|--------------------|
+|  | <b>F.700–F.799</b> |
+|--|--------------------|
+
+### **ISDN SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.800–F.849 |
+|--|-------------|
+
+## **UNIVERSAL PERSONAL TELECOMMUNICATION**
+
+|  |             |
+|--|-------------|
+|  | F.850–F.899 |
+|--|-------------|
+
+## **ACCESSIBILITY AND HUMAN FACTORS**
+
+|  |             |
+|--|-------------|
+|  | F.900–F.999 |
+|--|-------------|
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.746.15
+
+# Requirements for smart broadband network gateway in multimedia content transmission
+
+## Summary
+
+Recommendation ITU-T F.746.15 specifies requirements for smart broadband network gateway (BNG) in multimedia content transmission, and specifically describes the functional requirements and architecture, security requirements, typical application scenarios and use cases.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                                 |
+|---------|----------------|------------|-------------|--------------------------------------------------------------------------------------------|
+| 1.0     | ITU-T F.746.15 | 2022-12-14 | 16          | <a href="http://www.itu.int/publications/record/11.1002/1000/15189">11.1002/1000/15189</a> |
+
+## Keywords
+
+Interactive experience, network, smart BNG, timeliness.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                             | Page |
+|-----------------------------------------------------------------------------|------|
+| 1 Scope .....                                                               | 1    |
+| 2 References.....                                                           | 1    |
+| 3 Definitions .....                                                         | 1    |
+| 3.1 Terms defined elsewhere .....                                           | 1    |
+| 3.2 Terms defined in this Recommendation.....                               | 1    |
+| 4 Abbreviations and acronyms .....                                          | 1    |
+| 5 Conventions .....                                                         | 2    |
+| 6 Introduction of smart BNG based on artificial intelligence.....           | 3    |
+| 7 Functional requirements and architecture of smart BNG .....               | 3    |
+| 7.1 Overview of smart BNG for multimedia application scenarios .....        | 3    |
+| 7.2 Sub-functions in the layered functional architecture of smart BNG ..... | 4    |
+| 8 Security requirements of smart BNG .....                                  | 6    |
+| Appendix I – Scenarios for smart broadband network gateway .....            | 8    |
+| I.1 Smart class scenario of smart BNG.....                                  | 8    |
+| I.2 Smart family scenario of smart BNG .....                                | 9    |
+| I.3 Smart industry scenario of smart BNG .....                              | 10   |
+| Appendix II – Use cases for smart broadband network gateway.....            | 12   |
+| Bibliography.....                                                           | 15   |
+
+
+
+# Recommendation ITU-T F.746.15
+
+## Requirements for smart broadband network gateway in multimedia content transmission
+
+## 1 Scope
+
+This Recommendation specifies requirements for smart broadband network gateway (BNG) in multimedia content transmission, and specifically describes the functional requirements and architecture, security requirements, typical application scenarios and use cases.
+
+The scope of this Recommendation includes:
+
+- Functional requirements and architecture of smart BNG;
+- Security requirements of smart BNG.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T M.3080] Recommendation ITU-T M.3080 (2021), *Framework of artificial intelligence enhanced telecom operation and management (AITOM)*.
+
+[ITU-T M.3400] Recommendation ITU-T M.3400 (2000), *TMN management functions*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 broadband network gateway (BNG)** [b-ITU-T Q.3315]: The access point to the provider's IP network for wireline broadband services.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+None.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                                     |
+|-----|-------------------------------------|
+| 4G  | 4th-Generation Mobile Communication |
+| 5G  | 5th-Generation Mobile Communication |
+| AGV | Automated Guided Vehicle            |
+| AI  | Artificial Intelligence             |
+| AR  | Augmented Reality                   |
+
+|       |                                                             |
+|-------|-------------------------------------------------------------|
+| ARP   | Address Resolution Protocol                                 |
+| BNG   | Broadband Network Gateway                                   |
+| CPU   | Central Processing Unit                                     |
+| DI    | Digital Input                                               |
+| DO    | Digital Output                                              |
+| DSL   | Digital Subscriber Line                                     |
+| EPON  | Ethernet Passive Optical Network                            |
+| FCAPS | Fault, Configuration, Accounting, Performance, and Security |
+| FE    | Fast Ethernet                                               |
+| GE    | Gigabit Ethernet                                            |
+| GPON  | Gigabit Passive Optical Network                             |
+| GRE   | Generic Routing Encapsulation                               |
+| IP    | Internet Protocol                                           |
+| IPSec | Internet Protocol Security                                  |
+| IPTV  | Internet Protocol Television                                |
+| IS-IS | Intermediate System-to-Intermediate System                  |
+| ITMS  | Integrated Terminal Management System                       |
+| LoRa  | Long Range                                                  |
+| NAT   | Network Address Translation                                 |
+| OSPF  | Open Shortest Path First                                    |
+| PON   | Passive Optical Network                                     |
+| RIP   | Routing Information Protocol                                |
+| USB   | Universal Serial Bus                                        |
+| VLAN  | Virtual Local Area Network                                  |
+| VPN   | Virtual Private Network                                     |
+| VR    | Virtual Reality                                             |
+| VxLAN | Visual extensible Local Area Network                        |
+| WAN   | Wide Area Network                                           |
+
+## 5 Conventions
+
+In this Recommendation:
+
+- The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+- The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement needs not be present to claim conformance.
+
+## 6 Introduction of smart BNG based on artificial intelligence
+
+Smart BNG is designed to improve the speed of multimedia resources transmission and enhance the interaction experience of users. The smart BNG, based on artificial intelligence and advanced hardware equipment, can analyse user preferences and store user data to provide better service for smart family, enterprise and industry scenarios.
+
+Traditional BNG mainly provides network access functions for users. Compared to traditional BNG, smart BNG with an artificial intelligence (AI) computing chip supports the AI model inference function and enhances transmission capability for multimedia content. In addition, smart BNG can support intelligent scenarios, including but not limited to smart education, family and industry scenarios. Smart BNG can install related AI platforms or applications for different scenarios to support intelligent functions.
+
+From a functional perspective traditional BNG can be divided into a data gateway, multimedia gateway and collective control gateway. The data gateway is mainly used for data throughput and for providing delivery support for network protocols. The multimedia gateway supports audio and video content transmission. The collective control gateway supports home control and security service management on the network. Smart BNG has the basic functions of these three gateways, and also enhances these functions based on AI technology for different scenarios.
+
+## 7 Functional requirements and architecture of smart BNG
+
+Clause 7.1 provides an overview of the smart BNG for multimedia application scenarios, and clause 7.2 describes the layered functional architecture of smart BNG.
+
+### 7.1 Overview of smart BNG for multimedia application scenarios
+
+As is shown in Figure 1, the smart BNG is required to support different multimedia application scenarios, including smart industry, smart family, smart class and other scenarios. Therefore, the smart BNG is required to support the access of multiple multimedia devices and multiple ways to access the cloud, which stores multimedia content.
+
+![Figure 1 – Overview of smart BNG. The diagram shows a hierarchical structure. At the top is a cloud labeled 'Cloud (Content of smart industry, smart family, smart class, ...)'. Below the cloud is a large box labeled 'Smart BNG' which contains five stacked layers: 'Platform application layer', 'AI containerized functional component layer', 'Management and forwarding layer', 'Network interface layer', and 'Hardware infrastructure layer'. Below the Smart BNG box is another box labeled 'Multimedia devices'. A vertical line connects the cloud to the Smart BNG box, and another vertical line connects the Smart BNG box to the Multimedia devices box. The text 'F.746.15(22)' is at the bottom right of the diagram.](a234352dfaccdc24745c88eef7724cc6_img.jpg)
+
+F.746.15(22)
+
+Figure 1 – Overview of smart BNG. The diagram shows a hierarchical structure. At the top is a cloud labeled 'Cloud (Content of smart industry, smart family, smart class, ...)'. Below the cloud is a large box labeled 'Smart BNG' which contains five stacked layers: 'Platform application layer', 'AI containerized functional component layer', 'Management and forwarding layer', 'Network interface layer', and 'Hardware infrastructure layer'. Below the Smart BNG box is another box labeled 'Multimedia devices'. A vertical line connects the cloud to the Smart BNG box, and another vertical line connects the Smart BNG box to the Multimedia devices box. The text 'F.746.15(22)' is at the bottom right of the diagram.
+
+**Figure 1 – Overview of smart BNG**
+
+### 7.2 Sub-functions in the layered functional architecture of smart BNG
+
+Figure 2 outlines the sub-functions in the layered functional architecture of the smart BNG.
+
+![Figure 2 – Sub-functional architecture of smart BNG. The diagram shows five layers: Platform application layer, AI containerized functional component layer, Management and forwarding layer, Network interface layer, and Hardware infrastructure layer. A legend at the bottom indicates that solid boxes represent function blocks and dashed boxes represent logic layers.](cfda9df1319e04207eb28bcefd1dab7b_img.jpg)
+
+The diagram illustrates the sub-functional architecture of a smart BNG, organized into five layers:
+
+- Platform application layer:** Contains function blocks for Management platform, IPTV platform, AR/VR platform, and others (....).
+- AI containerized functional component layer:** Divided into two logic layers. The first logic layer, 'AI function set for application scenarios', includes function blocks for Smart industry, Smart family, Smart class, and others (...). The second logic layer, 'AI key technologies', includes function blocks for Image processing, Text processing, Voice processing, and others (...).
+- Management and forwarding layer:** Divided into two logic layers. The first logic layer, 'Management control', includes function blocks for FCAPS, Management interface, AI, Digital twin, and others (...). The second logic layer, 'Data forwarding', includes function blocks for Routing protocol, Tunnel technology, IP technology, and others (...).
+- Network interface layer:** Contains function blocks for USB, ZigBee, Bluetooth, Lora, FE/GE, DI/DO, Third-party, PON, DSL, LAN, WAN, Wi-Fi, 5G/4G, Peripherals, and others (...).
+- Hardware infrastructure layer:** Contains function blocks for CPU, Memory, AI computing chip, Codec chip, Network adapter, and others (...).
+
+Legend: Function block Logic layer
+
+F.746.15(22)
+
+Figure 2 – Sub-functional architecture of smart BNG. The diagram shows five layers: Platform application layer, AI containerized functional component layer, Management and forwarding layer, Network interface layer, and Hardware infrastructure layer. A legend at the bottom indicates that solid boxes represent function blocks and dashed boxes represent logic layers.
+
+**Figure 2 – Sub-functional architecture of smart BNG**
+
+#### 7.2.1 Hardware infrastructure layer
+
+The hardware infrastructure layer is aimed at supporting the basic environment for smart BNG. These hardware infrastructures add AI capabilities on the basis of the universal broadband network gateway. This layer includes the following hardware requirements:
+
+- 1) **Central processing unit (CPU):** The CPU is required to be capable of FP32 floating-point operations at least, so that the CPU can read the model data with higher precision into the memory without losing precision.
+- 2) **Memory:** It is required that the memory is sufficient to support the loading of large model files, the loading of inference data, and support high-speed reading and loading of large model files.
+- 3) **AI computing chip:** In order to ensure the AI model has a low inference delay, the smart BNG is required to use a dedicated chip to support the inference acceleration calculation function of the deep learning model based on the neural network.
+- 4) **Codec chip:** To reduce the load and occupancy of the CPU, the smart BNG is required to support a hardware codec chip to process multimedia data stored in smart BNG.
+- 5) **Network adapter:** The smart BNG is required to support high-bandwidth network cards to satisfy the transmission of large multimedia data.
+
+#### 7.2.2 Network interface layer
+
+The network interface layer is aimed at providing multiple interfaces of the smart BNG to support multiple access methods for the network and users. This layer includes the following requirements:
+
+- 1) **Wired access:** The smart BNG is required to support wired access to the network and provide wired access for users. Common wired access methods include passive optical network (PON) i.e., Ethernet passive optical network (EPON)/gigabit passive optical network (GPON), digital subscriber line (DSL), wide area network (WAN), local area network (LAN) and other methods.
+- 2) **Wireless access:** The smart BNG is required to support wireless access to the network and provide wireless access for users. Common wireless access methods include 5G/4G, WiFi, ZigBee, Lora, Bluetooth and other methods.
+- 3) **Third-party interface:** The smart BNG is required to support specific interfaces for special scenarios or applications to access some peripherals, such as voice interface, video interface and so on.
+
+#### 7.2.3 Management and forwarding layer
+
+As the BNG is required to be managed by a network management system and forward multimedia data from cloud to users, the BNG is required to support management control function and data forwarding function.
+
+The management control function mainly includes fault management, configuration management, accounting management, performance management, security management and interfaces between different management systems. For requirements of fault management, configuration management, accounting management, performance management, and security management refer to clauses 5, 6, 7, 8, and 9 of [ITU-T M.3400].
+
+The data forwarding function mainly includes routing protocols such as open shortest path first (OSPF), routing information protocol (RIP), intermediate system-to-intermediate system (IS-IS), etc., tunnel technology such as virtual extensible local area network (VxLAN), Internet protocol security (IPSec), generic routing encapsulation (GRE), etc., IP technology such as network address translation (NAT), etc., and other network communication technologies.
+
+The smart BNG is also required to support the above functions. In addition, it can use AI, digital twin, and other new technologies to enhance management functions. For requirements of AI enhanced telecom, operation and management, refer to [ITU-T M.3080].
+
+#### 7.2.4 AI containerized functional component layer
+
+The smart BNG is required to provide AI containerized functional components for different application scenarios. There are two types of components; AI functional components for application scenarios, and AI key technologies functional components.
+
+##### 7.2.4.1 AI function set for application scenarios
+
+These scenario functional components are composed of multiple AI functions based on different scenarios. AI application scenarios mainly include the following scenario functional components:
+
+- 1 **Smart industry scenario components:** This functional component is aimed at providing an AI function set related to the smart industry scenario. This scenario mainly includes machine vision, automated guided vehicle (AGV), augmented reality (AR) of equipment and other AI technologies.
+- 2 **Smart family scenario components:** This functional component is aimed at providing an AI function set related to the smart family scenario. This scenario mainly includes voice recognition for controlling furniture, face recognition for security, virtual reality (VR) for immersive movie viewing and other AI technologies.
+
+- 3      **Smart class scenario components:** This functional component is aimed at providing an AI function set related to the smart class scenario. This scenario mainly includes holographic projection for distance education, motion analysis for students, AR for auxiliary teaching and other AI technologies.
+
+Different application scenarios are based on different AI technologies and AI models. The smart BNG is required to support general AI functions for these scenarios, and these AI functions can be re-developed for special applications.
+
+##### 7.2.4.2 AI key technologies
+
+The AI key technology functional components are composed of general AI functions. These components mainly include the following AI functions:
+
+- 1)      **Image processing:** This functional component is aimed at providing AI technologies for image processing. It mainly includes image recognition, object detection, behaviour analysis and other AI technologies.
+- 2)      **Text processing:** This functional component is aimed at providing natural language processing for text processing. It mainly includes semantic analysis, keyword extraction and other AI technologies.
+- 3)      **Voice processing:** This functional component is aimed at providing AI technologies for voice processing. It mainly includes voice recognition, automatic interaction, voice synthesis and other AI technologies.
+
+Different applications are based on different AI technologies and AI models. The smart BNG is required to support multiple AI key technologies, and these technologies can be used in combination according to different requirements. These AI technologies can be used to train different AI models.
+
+#### 7.2.5 Platform application layer
+
+The platform application layer is aimed at supporting multimedia applications through smart BNG. The following platforms are recommended to be supported:
+
+- 1)      **Network management platform:** The smart BNG is required to be managed by upstream equipment or by a system such as integrated terminal management system (ITMS).
+- 2)      **IPTV platform:** The smart BNG is required to support Internet protocol television (IPTV) business for smart family scenario.
+- 3)      **AR/VR platform:** The smart BNG is required to support AR/VR business for smart family and smart industrial scenarios.
+
+The smart BNG is required to support general multimedia platforms, and the platform can be re-developed for special applications.
+
+## 8 Security requirements of smart BNG
+
+The smart BNG is recommended to support following security functions:
+
+- 1)      **Basic firewall function:** The smart BNG is recommended to support the opening and closing of protocol ports, and the protocols corresponding to pre-set common ports (such as 80, 8080, 21, 23, etc.).
+- 2)      **Access control function:** The smart BNG is recommended to support the implementation of corresponding access control policies based on parameters such as source/destination MAC address, IP quintuple, and time period.
+- 3)      **Content filtering function:** The smart BNG is recommended to filter content based on URL and keyword. It is also required to support setting black and white lists and implementing import and export operations.
+
+- 4) **Preventing ARP attack function:** The smart BNG is recommended to support MAC address and static binding with IP addresses and address resolution protocol (ARP) broadcast storm suppression function.
+- 5) **Content encryption and decryption function:** The smart BNG is recommended to support encryption and decryption of transmission content as requirements of users.
+
+## Appendix I
+
+### Scenarios for smart broadband network gateway
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix describes the typical scenarios of smart BNG. The typical scenarios include but are not limited to class, family and industry.
+
+### I.1 Smart class scenario of smart BNG
+
+Smart BNG can assist in many types of interactive classrooms, and help teachers better understand students. The smart BNG is recommended to support following interactive classrooms:
+
+- 1) **Physical interactive classroom:** It means that teachers and students carry out teaching activities in a physical classroom. The smart BNG can support various forms of interactions, including video system, voice system and other multimedia systems.
+- 2) **Online interactive classroom:** This teaching mode is not limited by time and space. Through the smart BNG, video, voice, image and other multimedia content can be transmitted between two or more different classrooms.
+- 3) **Cloud classroom:** This teaching mode can carry both physical classroom and online classroom, and support teaching cross-regional in real-time. The education system is deployed in the cloud, and delivers the education resources to the classroom through the smart BNG.
+
+![Diagram illustrating the deployment situation of smart BNG in a smart class scenario. At the top, an 'Education platform' cloud contains 'Live streaming', 'AI model training', and 'VPN networking' components. Below it, a 'Wide area network' cloud is connected via a dashed red VPN link. At the bottom, two 'Classroom' boxes are shown. Each classroom contains a 'Smart BNG' connected to a 'Teaching facility' (laptop) and a 'Camera'. The Smart BNGs are connected to the Wide area network via dashed red VPN links and solid black Logical links. A legend at the bottom indicates that solid lines represent Logical links and dashed red lines represent VPN links. The diagram is labeled F.746.15(22).](16c1175b5f05a4b55e6d396fc51b15b3_img.jpg)
+
+Diagram illustrating the deployment situation of smart BNG in a smart class scenario. At the top, an 'Education platform' cloud contains 'Live streaming', 'AI model training', and 'VPN networking' components. Below it, a 'Wide area network' cloud is connected via a dashed red VPN link. At the bottom, two 'Classroom' boxes are shown. Each classroom contains a 'Smart BNG' connected to a 'Teaching facility' (laptop) and a 'Camera'. The Smart BNGs are connected to the Wide area network via dashed red VPN links and solid black Logical links. A legend at the bottom indicates that solid lines represent Logical links and dashed red lines represent VPN links. The diagram is labeled F.746.15(22).
+
+Figure I.1 – The deployment situation of smart BNG in smart class scenario
+
+Figure I.1 shows the deployment situation of smart BNG in a smart class scenario. There are many smart terminals in the class, including tablets, screen projection equipment, electronic whiteboard and others. These teaching facilities and cameras in a classroom are connected with smart BNG. The AI model training is deployed on the education cloud platform. This module gets data through the smart BNG and trains related AI models, and includes handwriting recognition, and behaviour analysis to help teachers correct homework and understand students. The AI models are sent to smart BNG to do edge inference for smart terminal applications. Different classrooms connect with each other through smart BNG to build a virtual private network (VPN) link. Since the IP addresses of the smart BNG for school are private network addresses, they are allocated by the VPN networking module deployed on the education cloud platform. Through VPN links, the education application on cloud can send to multiple classrooms located in different regions.
+
+### I.2 Smart family scenario of smart BNG
+
+Multimedia applications are provided to the family through smart BNG. The smart BNG is recommended to support following applications for smart family:
+
+- 1) **Smart home:** The furniture has WI-FI modules which can be connected with smart BNG, and they can be controlled by a unified control panel or an application on mobile terminal. The furniture includes television, stereo, air conditioner, light and others. Users can control the furniture through a control panel, application or voice messages, and control messages are sent to furniture through smart BNG.
+- 2) **Family entertainment:** With the development of network and IT technology, people can experience cloud games and VR/AR games in the home. These games are rendered in the smart family cloud platform, and smart BNG unzips these videos. People play VR/AR, cloud games without any high-performance processor and graphics card, they just need gaming equipment to experience these games.
+- 3) **Health and security:** A camera in the home can monitor the elderly at home. If something unexpected happens, the security system will notify the family as soon as possible. If a stranger breaks into the house, it also can send out a warning alarm to protect personal and property safety.
+
+![Diagram illustrating the deployment situation of smart BNG in a smart family scenario. At the top, a cloud labeled 'Smart family platform' contains three service boxes: 'VR/AR games', 'IPTV', and 'Smart home service'. Below this is a cloud labeled 'Wide area network'. At the bottom, a dashed box labeled 'Home' contains several devices: 'IPTV', 'VR/AR game' (represented by a headset icon), 'Smart BNG' (represented by a router icon), 'Mobile terminal' (represented by a smartphone icon), 'Family security' (represented by a camera icon), and 'PC' (represented by a laptop icon). All devices in the 'Home' box are connected to the 'Smart BNG'. A double-headed arrow connects the 'Smart family platform' cloud to the 'Wide area network' cloud, which in turn connects to the 'Smart BNG' in the 'Home' box.](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+Diagram illustrating the deployment situation of smart BNG in a smart family scenario. At the top, a cloud labeled 'Smart family platform' contains three service boxes: 'VR/AR games', 'IPTV', and 'Smart home service'. Below this is a cloud labeled 'Wide area network'. At the bottom, a dashed box labeled 'Home' contains several devices: 'IPTV', 'VR/AR game' (represented by a headset icon), 'Smart BNG' (represented by a router icon), 'Mobile terminal' (represented by a smartphone icon), 'Family security' (represented by a camera icon), and 'PC' (represented by a laptop icon). All devices in the 'Home' box are connected to the 'Smart BNG'. A double-headed arrow connects the 'Smart family platform' cloud to the 'Wide area network' cloud, which in turn connects to the 'Smart BNG' in the 'Home' box.
+
+**Figure I.2 – The deployment situation of smart BNG in a smart family scenario**
+
+Figure I.2 shows the deployment situation of a smart BNG in a smart family scenario. There are many smart terminals in the home, including IPTV, screen projection equipment, VR/AR equipment and others. These smart terminals and cameras in the home are connected with smart BNG. The VR/AR games and IPTV are deployed on the smart family cloud platform. This module renders VR/AR games, and sends them to game terminals through smart BNG. The content of IPTV is sent to smart BNG to provide service. The smart family cloud platform can provide other services, including health monitoring, security, and so on.
+
+### I.3 Smart industry scenario of smart BNG
+
+Multimedia applications are provided to industry through smart BNG. The smart BNG is recommended to support following applications for smart industry:
+
+- 1) **Machine vision:** The camera in industry can collect image data and upload data to a smart industry cloud platform to train AI models through smart BNG. After training, these AI models are sent to corresponding equipment. The AI models can be used in object sorting, quality inspection, object measurement and other industry applications. The smart BNG do inference based on AI trained models for these applications.
+- 2) **Smart office service:** The smart office services are deployed in the smart industry cloud platform. And the branches can use these services through smart BNG. These services can be used directly on the cloud, or can be downloaded locally.
+- 3) **Security:** Cameras in industry can monitor staff working. If something dangerous happens, the security system will notify the whole industry as soon as possible, and it also can send out a warning alarm to protect personal and property safety.
+
+![Diagram illustrating the deployment situation of smart BNG in a smart industry scenario. A central 'Wide area network' cloud is connected to three sites: Site A, Site B, and Site C. Site A and Site C each have a 'Smart BNG' connected to three computers. Site B has a 'Smart BNG' connected to a 'Camera' and three computers. Above the central cloud is a 'Smart industry platform' cloud containing 'Smart office service', 'AI model training', and 'VPN orchestrator' modules. Control links (blue dashed lines with arrows) connect the platform to the central cloud and the Smart BNGs at Sites A and C. VPN links (red dashed lines) connect the Smart BNGs at Sites A, B, and C through the central cloud. Logical links (solid black lines) connect the Smart BNGs to the terminals at each site. A legend at the bottom identifies the link types: solid line for Logical link, dashed red line for VPN link, and dashed blue line with arrow for Control link. The text 'F.746.15(22)' is in the bottom right corner.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+Diagram illustrating the deployment situation of smart BNG in a smart industry scenario. A central 'Wide area network' cloud is connected to three sites: Site A, Site B, and Site C. Site A and Site C each have a 'Smart BNG' connected to three computers. Site B has a 'Smart BNG' connected to a 'Camera' and three computers. Above the central cloud is a 'Smart industry platform' cloud containing 'Smart office service', 'AI model training', and 'VPN orchestrator' modules. Control links (blue dashed lines with arrows) connect the platform to the central cloud and the Smart BNGs at Sites A and C. VPN links (red dashed lines) connect the Smart BNGs at Sites A, B, and C through the central cloud. Logical links (solid black lines) connect the Smart BNGs to the terminals at each site. A legend at the bottom identifies the link types: solid line for Logical link, dashed red line for VPN link, and dashed blue line with arrow for Control link. The text 'F.746.15(22)' is in the bottom right corner.
+
+**Figure I.3 – The deployment situation of smart BNG in smart industry scenario**
+
+Figure I.3 shows the deployment situation of smart BNG in a smart industry scenario. The terminals used in industry include cameras, computers, AGVs, and other equipment. These terminals are connected with the smart BNG. The AI model training is deployed on the industry cloud platform. This module gets data through smart BNG and trains related AI models for various applications to improve production. The AI models are sent to smart BNG to do edge inference for image identification applications. Different branches connect with each other through smart BNG to build VPN links. If the IP addresses of the company are public network addresses, they can build VPN links directly. Otherwise, VPN links can be built by cloud as in the smart class scenario. The VPN orchestrator deployed on the industry cloud platform can manage VPN links based on control links.
+
+## Appendix II
+
+### Use cases for smart broadband network gateway
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Appendix II describes use cases for smart broadband network gateway.
+
+Table II.1 describes live streaming in a smart education scenario.
+
+**Table II.1 – Live streaming in education scenario**
+
+| Title                      | Live streaming in a smart education scenario                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+|----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Description                | <p>Live video is a kind of teaching method in a smart education scenario. The education platform forwards live streaming from different sources through VPN tunnels among the smart BNGs. With VPN tunnels the platform sends living streaming by multicast instead of unicast. The process consists of the following three steps:</p> <ol style="list-style-type: none"> <li>1) The education platform gets live video streaming from different sources by unicast;</li> <li>2) It builds VPN tunnels among multiple smart BNGs;</li> <li>3) The platform sends the living streaming through tunnels with multicast and the smart BNGs receive streaming from VPN tunnels.</li> </ol> |
+| Roles                      | Network service provider, live video sources, classes                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+| Figure (optional)          | <img alt="Diagram of live streaming in a smart education scenario. At the top, an 'Education platform' cloud contains 'Education video library', 'Live streaming engine', and 'VPN network'. It is connected to three 'Live video source' boxes. Below it, a 'Wide area network' cloud is connected via dashed red lines to two 'Smart BNG' units. Each 'Smart BNG' is connected to a 'Live streaming receiver' box. The 'Smart BNG' and 'Live streaming receiver' are grouped into 'Classroom 1' and 'Classroom 2' dashed boxes. The label F.746.15(22) is in the bottom right." data-bbox="582 1093 1428 1753" src="b03533cc9198ad21d619252486969839_img.jpg"/>                      |
+| Pre-conditions (optional)  | The VPN among the smart BNGs and the education platform should be built.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Post-conditions (optional) |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+
+Table II.2 describes a family VR/AR games use case in a smart family scenario.
+
+**Table II.2 – Family VR/AR games in smart family scenario**
+
+| Title                      | Family VR/AR games in smart family scenario                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+|----------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Description                | <p>The smart BNG has an intelligent and open system to run various kinds of applications and it also supports VR/AR games in a family scenario. The smart family platform provides the VR/AR game service and rendering service. The smart BNG runs VR/AR game applications and provides computing resources to support VR/AR streaming handling. The process consists of the following two steps:</p> <ol style="list-style-type: none"> <li>1) The smart BNG installs the VR/AR game application and it links VR/AR terminals via Wi-Fi.</li> <li>2) The smart family platform sends VR/AR game rendered video streaming to the smart BNG and the VR/AR application installed in the BNG handles the streaming and sends to the terminal according to the related command.</li> </ol>                                                                                                                                                               |
+| Roles                      | Network service provider, family VR/AR games provider, player                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Figure (optional)          | <img alt="Diagram illustrating the architecture of family VR/AR games in a smart family scenario. At the top, a light blue cloud labeled 'Smart family platform' contains two boxes: 'VR/AR games service' and 'Rendering engine'. Below it, a dark blue cloud labeled 'Wide area network' is connected via a double-headed arrow. At the bottom, a dashed box labeled 'Home' contains a 'Smart BNG' (represented by a router icon), a 'VR/AR game application' (represented by a box), and a person wearing a VR headset. The Smart BNG is connected to the Wide area network and to the VR/AR game application. The VR/AR game application is connected to the person wearing the VR headset. A Wi-Fi symbol indicates a connection between the Smart BNG and the VR headset. The reference 'F.746.15(22)' is shown in the bottom right corner of the diagram area." data-bbox="738 869 1276 1753" src="04b5df354878bcb2868795f8dbdf2726_img.jpg"/> |
+| Pre-conditions (optional)  | The VR/AR game applications can be installed in the smart BNG.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+| Post-conditions (optional) |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+
+Table II.3 describes AI model training for machine vision in an industry scenario.
+
+**Table II.3 – AI model training for machine vision in industry scenario**
+
+| Title                      | AI model training for machine vision in industry scenario                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|----------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Description                | <p>In machine vision use case (such as industrial quality inspection, intelligent picking, etc.), the machine vision AI model needs to be trained when new samples appear.</p> <p>The smart industry platform has different components including AI platform environment, AI model library and vision model training engine, etc. The smart industry platform provides computing resources for machine vision AI model training. The process consists of the following three steps:</p> <ol style="list-style-type: none"> <li>1) The samples are produced for machine vision AI model training at the production site. The smart BNG collects all samples and sends them to the smart industry platform through a VPN between smart BNG and the platform.</li> <li>2) The smart industry platform trains the machine vision AI model after receiving the production samples.</li> <li>3) The platform sends the trained vision inference model to the smart BNG, and the smart BNG uses the AI model to do inference for productions.</li> </ol> |
+| Roles                      | Network service provider, smart industry platform vendor, industry manufacturer.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+| Figure (optional)          | <img alt="Diagram illustrating the AI model training architecture. At the top, a light blue cloud labeled 'Smart industry platform' contains three boxes: 'AI platform', 'AI model library', and 'Vision model training engine'. Below it, a dark blue cloud labeled 'Wide area network' is connected via a red dashed double-headed arrow. At the bottom, a dashed box labeled 'Production site' contains a 'Smart BNG' (represented by a router icon) connected to two boxes: 'Samples collection' and 'Vision inference'. A red dashed double-headed arrow connects the Smart BNG to the Wide area network cloud." data-bbox="737 1012 1276 1881" src="dfe0567f7f23e65eac31fd8a281ea347_img.jpg"/> <p style="text-align: right;">F.746.15(22)</p>                                                                                                                                                                                                                                                                                              |
+| Pre-conditions (optional)  | The VPN between the smart BNG and the smart industry platform should be built.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| Post-conditions (optional) |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+
+## Bibliography
+
+[b-ITU-T Q.3315] Recommendation ITU-T Q.3315 (2015), *Signalling requirements for flexible network service combination on broadband network gateway*.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: International sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+Recommendation
+
+**ITU-T F.746.19 (12/2025)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+**Requirements for conversion and collaboration methods in a hybrid work environment**
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.746.19
+
+## Requirements for conversion and collaboration methods in a hybrid work environment
+
+## Summary
+
+Hybrid work environments refer to a method of collaboration among users in different physical locations. With the recent spread of epidemics such as COVID-19, non-face-to-face meetings and remote work are becoming more popular, and it is expected that they will continue in a hybrid way even though the epidemic has decreased or dissipated in the future.
+
+However, hybrid work environment can lead to a lack of mutual understanding when conducting a conversation, and a discussion based on false facts can lead to inappropriate conclusions. In addition, there are cases where it is difficult to prepare minutes because the other party's exact intention is not understood.
+
+The purpose of Recommendation ITU-T F.746.19 is to improve hybrid work methods through artificial intelligence technology to improve the efficiency and accuracy of conversation in a hybrid environment.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.746.19 | 2025-12-14 | 21          | 11.1002/1000/16579 |
+
+## Keywords
+
+Conversation system, hybrid work environment.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2026
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|      |                                                                                                   |    |
+|------|---------------------------------------------------------------------------------------------------|----|
+| 1    | Scope.....                                                                                        | 1  |
+| 2    | References.....                                                                                   | 1  |
+| 3    | Definitions .....                                                                                 | 1  |
+| 3.1  | Terms defined elsewhere .....                                                                     | 1  |
+| 3.2  | Terms defined in this Recommendation .....                                                        | 1  |
+| 4    | Abbreviations and acronyms .....                                                                  | 1  |
+| 5    | Conventions .....                                                                                 | 1  |
+| 6    | Background.....                                                                                   | 2  |
+| 7    | Comparison of typical face-to-face meeting and hybrid work environment .....                      | 3  |
+| 7.1  | Agenda.....                                                                                       | 3  |
+| 7.2  | Discussion.....                                                                                   | 3  |
+| 7.3  | Meeting minutes .....                                                                             | 3  |
+| 7.4  | Minutes sharing .....                                                                             | 3  |
+| 8    | Benefits of real-time document co-authoring in a hybrid work environment .....                    | 4  |
+| 8.1  | Traditional document co-authoring .....                                                           | 4  |
+| 8.2  | Real-time document co-authoring with emotion .....                                                | 4  |
+| 8.3  | Benefits of document co-authoring .....                                                           | 4  |
+| 9    | General requirements of conversation and collaboration methods in a hybrid work environment ..... | 5  |
+| 9.1  | Functional requirements .....                                                                     | 5  |
+| 9.2  | Non-functional requirements .....                                                                 | 5  |
+| 9.3  | Asynchronous communication requirements .....                                                     | 6  |
+| 10   | Requirements of components for real-time document co-authoring function.....                      | 7  |
+| 10.1 | Master view .....                                                                                 | 7  |
+| 10.2 | User view (individual view) .....                                                                 | 7  |
+| 10.3 | Reflection of real-time modifications.....                                                        | 7  |
+| 10.4 | Revision alert for original author's wording.....                                                 | 7  |
+| 10.5 | Reflection of personal status .....                                                               | 7  |
+| 10.6 | Definition of personal status.....                                                                | 7  |
+| 11   | Hybrid work environment workflow .....                                                            | 8  |
+| 11.1 | Real-time document co-authoring .....                                                             | 8  |
+| 11.2 | Hybrid meeting environment.....                                                                   | 9  |
+| 11.3 | Speech recognition .....                                                                          | 9  |
+| 11.4 | Face recognition .....                                                                            | 9  |
+| 11.5 | Speaker identification.....                                                                       | 9  |
+| 11.6 | Question and dialogue processing .....                                                            | 9  |
+| 11.7 | Emotion analysis .....                                                                            | 10 |
+
+|                                    | Page |
+|------------------------------------|------|
+| 11.8 Statistical analysis .....    | 10   |
+| 11.9 Authentication .....          | 10   |
+| 11.10 Domain knowledge-based ..... | 10   |
+| 11.11 Guest book.....              | 10   |
+
+# Recommendation ITU-T F.746.19
+
+## Requirements for conversion and collaboration methods in a hybrid work environment
+
+# 1 Scope
+
+This Recommendation includes:
+
+- Requirements for conducting a hybrid work environment.
+- Use cases regarding the meeting method for a hybrid work environment.
+- Definition of the meeting workflow for a hybrid work environment.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T F.746.3] Recommendation ITU-T F.746.3 (2015), *Intelligent question answering service framework*.
+
+[IEEE P3300] IEEE P3300 (2022), *Moving Picture Audio and Data Coding by Artificial Intelligence (MPAI) Technical Specification Multimodal Conversion Version 1.2*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+None.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 hybrid work:** A flexible working model where employees split their time between a physical workplace and a remote location.
+
+NOTE – Examples of a remote location are the employee's home or another workspace.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviation and acronym:
+
+KB Knowledge Base
+
+UI User Interface
+
+VPN Virtual Private Network
+
+## 5 Conventions
+
+In this Recommendation:
+
+The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+The keywords "**can optionally**" and "**may**" indicate an optional requirement which is permissible, without implying any sense of being recommended. These terms are not intended to imply that the vendor's implementation must provide the option, and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Background
+
+With the recent spread of epidemics such as COVID-19, non-face-to-face meetings and remote work are becoming more popular, and it is expected that they will continue in a hybrid way even though the epidemic decreases or dissipates in the future. In response to this situation, this Recommendation identifies requirements and provides guidance to overcome these issues.
+
+Traditional remote workers have simply accessed the company's internal systems via a virtual private network (VPN), etc., and have used online meeting tools when holding meetings.
+
+However, this work approach is not perfectly efficient. Additionally, not only is it difficult to determine whether the stakeholders have empathy for the issue, but it is difficult to check the work efficiency and status. Moreover, it is not easy to respond to the issue from the point of view of the stakeholders who manage the team or a specific task.
+
+For example, a person may want to share and explain some discussion issues with only a shared screen during an online meeting. However, in this way it is not easy to understand the workflow or contextual information of the discussion. These issues can eventually produce an incorrect conclusion. Accordingly, there is a need for better working methods in which the participants and stakeholders can correctly understand the work environment and empathize with any discussion issues when they arise. Clause 7 presents a comparison between traditional meetings and meetings conducted in a hybrid environment.
+
+Figure 1 illustrates how on-site and remote workers collaborate within a hybrid work environment through an artificial intelligence (AI)-assisted meeting system and real-time document co-authoring.
+
+![Diagram illustrating a hybrid work environment. On the left, an 'On-site worker' icon is shown. In the center, a box labeled 'Hybrid meeting' contains icons for 'Co-authoring with emotion' and 'Meeting minutes and distribution'. On the right, a 'Remote worker' icon is shown. Double-headed arrows connect the On-site worker to the Hybrid meeting box, and the Hybrid meeting box to the Remote worker. A small text 'F.746.19(25)' is visible at the bottom right of the diagram.](731f533b0599c8e42a063f06e4332045_img.jpg)
+
+The diagram shows a central box labeled "Hybrid meeting" containing three items: "Co-authoring with emotion" (represented by a document and pencil icon), "Meeting minutes and distribution" (represented by a document icon), and a video call icon at the top. To the left of this box is an "On-site worker" icon (a person at a desk). To the right is a "Remote worker" icon (a person with a laptop and signal waves). Double-headed arrows connect the On-site worker to the Hybrid meeting box, and the Hybrid meeting box to the Remote worker. A small text "F.746.19(25)" is visible at the bottom right of the diagram.
+
+Diagram illustrating a hybrid work environment. On the left, an 'On-site worker' icon is shown. In the center, a box labeled 'Hybrid meeting' contains icons for 'Co-authoring with emotion' and 'Meeting minutes and distribution'. On the right, a 'Remote worker' icon is shown. Double-headed arrows connect the On-site worker to the Hybrid meeting box, and the Hybrid meeting box to the Remote worker. A small text 'F.746.19(25)' is visible at the bottom right of the diagram.
+
+**Figure 1 – Conversation in a hybrid work environment**
+
+Hybrid work differs from conventional remote work by enabling on-site and remote participants to engage in simultaneous and seamless communication, fostering more effective real-time collaboration. This structure enables real-time collaboration between on-site and remote participants
+
+by integrating AI-based models for speech, emotion, and domain knowledge analysis, ensuring consistent understanding and efficient workflow management.
+
+## 7 Comparison of typical face-to-face meeting and hybrid work environment
+
+A typical meeting consists of elements such as agenda, discussions, minutes, and sharing, as shown in Figure 2. These are basic components. The basic components can be implemented as hybrid work methods through input/output mechanisms due to the artificial intelligence requirements subdivided in clause 9.
+
+There are technical differences between the typical meeting and a hybrid work environment. In a hybrid work environment, factors such as fact-checking based on domain knowledge, speaker identification, authentication, and emotion recognition, which are introduced in clause 8, are added.
+
+![Figure 2: Basic components of typical meeting. A flowchart showing four stages: Agenda, Discussion, Meeting minutes, and Minutes sharing. Each stage is in a box with an icon below it: Agenda (hand with pen on clipboard), Discussion (speech bubble), Meeting minutes (stack of papers), and Minutes sharing (person with laptop and speech bubble).](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+```
+graph LR; A[Agenda] --> B[Discussion]; B --> C[Meeting minutes]; C --> D[Minutes sharing];
+```
+
+Figure 2: Basic components of typical meeting. A flowchart showing four stages: Agenda, Discussion, Meeting minutes, and Minutes sharing. Each stage is in a box with an icon below it: Agenda (hand with pen on clipboard), Discussion (speech bubble), Meeting minutes (stack of papers), and Minutes sharing (person with laptop and speech bubble).
+
+Figure 2 – Basic components of typical meeting
+
+### 7.1 Agenda
+
+The agenda of the meeting is set before the meeting starts. It can also identify the topic by using words or phrases that are frequently repeated within the meeting. A suitable domain is selected according to the agenda, and it is possible to check whether the content of the speech is consistent with the topic of the meeting through the model within the domain.
+
+### 7.2 Discussion
+
+When a discussion starts during the meeting, the knowledge base (KB) is used to check whether the speaker's statements are factually accurate. If not, a note requesting reconfirmation can be added to the meeting minutes.
+
+### 7.3 Meeting minutes
+
+Minutes are important outcomes that record the contents of the meeting so that the main points can be addressed. In this proposal, it is easy to manage the history by collecting and recording speaker separation recognition, summary of main contents, nuances of the speaker, speaking time, etc.
+
+The detailed user interface (UI) of the meeting minutes can be suggested through further detailed work afterwards.
+
+### 7.4 Minutes sharing
+
+The meeting minutes are automatically distributed to all attendees based on the guestbook, and if the person in charge and the deadline for handling is specified in the meeting minutes, important matters are notified to the person in charge to prevent omissions and improve work accuracy.
+
+## **8 Benefits of real-time document co-authoring in a hybrid work environment**
+
+This clause discusses the distinction between traditional paperwork and real-time document co-authoring. It also highlights the advantages of co-authoring documents in real time within a hybrid environment.
+
+### **8.1 Traditional document co-authoring**
+
+Traditional document co-authoring involves one person working on a document at a time. While the document can be shared with others, simultaneous collaboration is not possible.
+
+Since then, due to the popularization of the cloud, joint editing has become possible by updating files on the server, but it has not been easy to obtain accurate feedback and contextual information from each other.
+
+### **8.2 Real-time document co-authoring with emotion**
+
+Real-time document co-authoring enables multiple people to collaborate on a document simultaneously. Users can view the document in real time and observe changes made by others. Additionally, the emotional state of the original author and other users is identified and stored as metadata along with the text, facilitating effective communication. To enhance contextual understanding and improve interpretation of collaborative intent, the concept of personal status is introduced, capturing users' emotional and cognitive states as part of the co-authoring metadata.
+
+### **8.3 Benefits of document co-authoring**
+
+The advantages of collaborative document editing can be summarized as follows.
+
+#### **8.3.1 Enhanced collaboration**
+
+Real-time co-authoring of documents enhances collaboration among employees. Users can work simultaneously on documents, view changes made by others, share ideas, provide feedback, and complete documents faster and more efficiently.
+
+#### **8.3.2 Increased productivity**
+
+Real-time co-authoring of documents helps improve employee productivity. Users can collaborate on documents simultaneously, reducing the time required to complete them.
+
+#### **8.3.3 Improved communication**
+
+Real-time co-authoring of documents enhances communication between employees. Simultaneous collaboration and visibility of changes made by others help prevent misunderstandings.
+
+#### **8.3.4 Increased flexibility**
+
+Real-time co-authoring of documents provides flexibility for employees. They can work on documents from home while others work from the office, allowing them to complete documents without being constrained by commuting times.
+
+The conversation and collaboration methods requirements necessary to realize these advantages are as follows.
+
+Figure 3 illustrates the concept of co-authoring, showing that co-authoring depicts a collaborative editing space where stakeholders can review content, provide comments, and express emotional feedback. This figure demonstrates an integrated environment that supports efficient collaboration and communication during document authoring.
+
+![Figure 3: A screenshot of a document snippet illustrating co-authoring. At the top, there are three icons: a smiling face with heart eyes, a neutral face, and a face with wide eyes. Below the icons is a text box containing the following text: 'This is sample test for co-authoring. Every stakeholder can review the content and provide comments including emotional feedback. This method is highly effective for collaborating with multiple stakeholders during the document authoring process.' The text 'provide comments' and 'multiple stakeholders' are underlined. The entire image is enclosed in a blue border.](967c30813761a8952ecc5e16bf42ea45_img.jpg)
+
+Figure 3: A screenshot of a document snippet illustrating co-authoring. At the top, there are three icons: a smiling face with heart eyes, a neutral face, and a face with wide eyes. Below the icons is a text box containing the following text: 'This is sample test for co-authoring. Every stakeholder can review the content and provide comments including emotional feedback. This method is highly effective for collaborating with multiple stakeholders during the document authoring process.' The text 'provide comments' and 'multiple stakeholders' are underlined. The entire image is enclosed in a blue border.
+
+F.746.19(25)
+
+**Figure 3 – Co-authoring in a hybrid work environment**
+
+## **9 General requirements of conversation and collaboration methods in a hybrid work environment**
+
+The conversation and collaboration methods are recommended to enable seamless real-time communication, facilitating both synchronous and asynchronous collaboration. The detailed requirements are as follows.
+
+### **9.1 Functional requirements**
+
+To ensure the system meets the intended operational objectives and delivers value to its users, it is recommended to define and implement the following functional requirements. These requirements focus on the specific features and behaviours the system must support to facilitate effective communication and collaboration in a hybrid work environment.
+
+#### **9.1.1 Real-time communication**
+
+It is recommended to include features that allow for smooth and uninterrupted live interactions. This should encompass high-quality video calls, instant messaging with minimal latency, efficient file sharing capabilities, and comprehensive user status indicators, such as showing whether a user is online, offline, or busy, ensuring real-time awareness among participants.
+
+#### **9.1.2 Access controls and notifications**
+
+It is recommended to implement access controls that are dynamically based on user roles, such as administrative privileges or regular user permissions. Furthermore, the system is recommended to allow users to customize their notification preferences to reduce distractions and improve usability based on individual needs or organizational policies.
+
+#### **9.1.3 Multi-platform compatibility**
+
+It is recommended to ensure that the system operates smoothly and consistently across various platforms and devices, including desktops, laptops, smartphones, and tablets, providing a uniform experience regardless of the hardware or operating system being used.
+
+### **9.2 Non-functional requirements**
+
+To enhance overall performance and usability, it is recommended to adhere to the following non-functional requirements:
+
+#### **9.2.1 Performance optimization**
+
+It is recommended to be optimized to ensure quick and efficient responses, minimizing delays even during peak usage periods.
+
+#### **9.2.2 Scalability**
+
+It is recommended to design the system to handle an increasing number of users or concurrent sessions without compromising performance or reliability.
+
+#### **9.2.3 Security**
+
+The system is recommended to implement robust security measures, including end-to-end encryption, multi-factor authentication, and regular security updates to protect user data and prevent unauthorized access.
+
+#### **9.2.4 Compliance**
+
+It is recommended to ensure that the system adheres to all relevant legal and regulatory standards, including data privacy laws and industry-specific compliance requirements.
+
+#### **9.2.5 Accessibility and usability**
+
+It is recommended to incorporate features that promote accessibility for a diverse range of users, including those with disabilities. This should include an intuitive interface, assistive technology support, and a modular architecture that facilitates straightforward maintenance, updates, and the addition of new features.
+
+### **9.3 Asynchronous communication requirements**
+
+For communication that does not occur in real time, it is recommended to provide robust support for asynchronous collaboration. This includes features like cloud-based file sharing that allows easy access from multiple locations, maintaining a comprehensive and searchable history of past conversations, and seamless integration with other widely used collaboration tools to ensure continuity and efficiency in workflows.
+
+#### **9.3.1 Standardized template utilization**
+
+Standardized template utilization is recommended to maintain consistency.
+
+#### **9.3.2 Summary and action items inclusion**
+
+Every communication is recommended to include a core summary and a list of action items.
+
+#### **9.3.3 Centralized document repository**
+
+Centralized document repository can optionally store all asynchronous communication materials.
+
+#### **9.3.4 Searchable format**
+
+A searchable format is required to ensure that documents and messages are stored in a text-based format.
+
+#### **9.3.5 Categorization and tagging system**
+
+Categorization and tagging system are required to organize documents and communication material.
+
+#### **9.3.6 Feedback and participation encouragement**
+
+Feedback and participation functions are recommended to be provided.
+
+#### **9.3.7 Feedback system**
+
+Asynchronous communication system is recommended to provide functionalities for submitting opinions, questions, and feedback.
+
+#### **9.3.8 Updates and reminder system**
+
+Updates and reminder system is recommended to provide updates on project progress, significant milestones, and changes.
+
+# **10 Requirements of components for real-time document co-authoring function**
+
+A hybrid work environment is a working approach that combines traditional offline work with digital technology, and it is gradually gaining importance. In such an environment, collaborative document authoring refers to the process of multiple members within an organization working together to create, edit, and manage documents. To carry out these tasks, it is required to define the requirements of the components.
+
+### **10.1 Master view**
+
+The master view is required to allow monitoring of the master's operations. Users can observe the actions of the master and provide feedback, ensuring project quality and correctness.
+
+### **10.2 User view (individual view)**
+
+The user view is required to enable real-time concurrent document co-authoring, allowing each person to co-author the document by performing activities such as writing, editing, and deleting within their own view.
+
+### **10.3 Reflection of real-time modifications**
+
+Co-authoring in a hybrid work environment is required to reflect real-time changes, additions, and deletions made by multiple users instantly.
+
+### **10.4 Revision alert for original author's wording**
+
+The co-authoring function in a hybrid work environment is required to send an alert to the original author when another user modifies their text. The final document is required to be revised only upon the original author's acceptance of the modifications.
+
+### **10.5 Reflection of personal status**
+
+Co-authoring documents in a hybrid work environment is required to store each user's personal status during initial sentence creation, correction, and deletion, along with the text, as metadata containing semantic information. This allows contextual information to be retained, even if a third party views the document. It is particularly useful for understanding personal status in documents such as movie or drama scenarios or scripts.
+
+### **10.6 Definition of personal status**
+
+A data type representing the ensemble of information internal to a person expressed by 3 factors (cognitive state, emotion, social attitude) conveyed by one or more modalities (speech, face, and gesture).
+
+#### **10.6.1 Limit of personal status**
+
+Personal status is a subjective and complex phenomenon that is challenging to define and standardize universally, given variations among individuals and cultures. In the context of document co-authoring, the emotions referred to herein pertain to the fundamental emotions to be employed. However, it is required to be noted that the definition of personal status can optionally undergo partial modifications influenced by psychology and other factors.
+
+#### **10.6.2 Personal status items for real-time document co-authoring**
+
+Table 1 categorizes personal status as defined in [IEEE P3300], specifically reclassified for use during collaborative document co-authoring.
+
+**Table 1 – Personal status items for document co-authoring**
+
+| Category   | Description                                                                                                                       |
+|------------|-----------------------------------------------------------------------------------------------------------------------------------|
+| Positive   | This status is used when feedback or suggestions are based on positive emotions, including satisfaction, happiness, or gratitude. |
+| Negative   | Indicates feedback expressing dissatisfaction, disappointment, or concern, signalling a need for improvement.                     |
+| Neutral    | Represents factual or objective feedback without an emotional tendency, useful for focusing on the essence of the issue.          |
+| Curious    | Used to express curiosity or interest in new ideas or proposals, and may involve questions or requests for further explanation.   |
+| Interested | Indicates interest or enthusiasm for a particular idea or proposal, showing a willingness to actively participate.                |
+
+#### 10.6.3 Definition of factors for personal status
+
+The personal status is recommended to be identified through the analysis of the user's facial expressions, gestures and voice (see Table 2).
+
+**Table 2 – Determining factor item of personal status**
+
+| Data Type          | Description                                                                                    |
+|--------------------|------------------------------------------------------------------------------------------------|
+| Facial expressions | Analysis of facial muscle movements and expressions to interpret emotions.                     |
+| Gestures           | Examination of body movements, hand gestures, and postures to understand emotional cues.       |
+| Voice data         | Evaluation of vocal tone, pitch, volume, and speech patterns to extract emotional information. |
+
+## 11 Hybrid work environment workflow
+
+### 11.1 Real-time document co-authoring
+
+In this workflow (see Figure 4), three users collaboratively edit content in the output document. Each user's emotional state is recorded during creation, editing or deletion of text. The system outputs the final text, emotional context for each revision and a semantic history log capturing both author and editor emotions.
+
+![Diagram of the real-time document co-authoring workflow. On the left, under 'Input', are three users: User 1, User 2, and User 3. User 1 sends 'Create (Text, emotion)' to a central 'Document' box. User 2 sends 'Edit (Text, emotion)' to the 'Document' box. User 3 sends 'Delete (Text, emotion)' to the 'Document' box. On the right, under 'Output', the 'Document' box points to three results: 'Final text', 'Emotion at each text', and 'History tracking information with semantic status'.](c036e2540a94b31357ceb0002f0cacab_img.jpg)
+
+```
+
+graph LR
+    subgraph Input
+        U1((User 1)) -- "Create (Text, emotion)" --> D[Document]
+        U2((User 2)) -- "Edit (Text, emotion)" --> D
+        U3((User 3)) -- "Delete (Text, emotion)" --> D
+    end
+    subgraph Output
+        D --> F[Final text]
+        D --> E[Emotion at each text]
+        D --> H[History tracking information with semantic status]
+    end
+  
+```
+
+Diagram of the real-time document co-authoring workflow. On the left, under 'Input', are three users: User 1, User 2, and User 3. User 1 sends 'Create (Text, emotion)' to a central 'Document' box. User 2 sends 'Edit (Text, emotion)' to the 'Document' box. User 3 sends 'Delete (Text, emotion)' to the 'Document' box. On the right, under 'Output', the 'Document' box points to three results: 'Final text', 'Emotion at each text', and 'History tracking information with semantic status'.
+
+F.746.19(25)
+
+**Figure 4 – Real-time document co-authoring workflow**
+
+### 11.2 Hybrid meeting environment
+
+The structure illustrated in Figure 5 provides an extended representation of the basic meeting components described in clause 7, namely agenda, discussion, meeting minutes and minutes sharing.
+
+![Figure 5 – Hybrid meeting environment workflow diagram](724c7777b608e53be38b12b6fb3c43bc_img.jpg)
+
+The diagram illustrates the hybrid meeting environment workflow. It starts with three input sources: Speech, Face, and Text (Material). Speech is processed by a Speech recognition block to produce Text. Face is processed by a Face recognition block to produce an Image. Both Text and Image are inputs to a Speaker identification block. The Speaker identification block outputs Text to four parallel processing blocks: Question and dialogue processing, Emotion analysis, Statistical analysis, and Authentication. Question and dialogue processing outputs Text (Fact) and Text (Speech) to a Domain knowledge-based block. Emotion analysis outputs Text (Emotion). Statistical analysis outputs Text (Statistical Info.). Authentication outputs an Authentication ID to a Guest book block, which then outputs Text (Participants). All five outputs (Text (Fact), Text (Speech), Text (Emotion), Text (Statistical Info.), and Text (Participants)) are inputs to a Meeting minutes and sharing block. This block outputs Text (Personal), Text (Deadline), and Text (Work items) to a Notification block. The diagram is labeled F.746.19(25).
+
+Figure 5 – Hybrid meeting environment workflow diagram
+
+**Figure 5 – Hybrid meeting environment workflow**
+
+While Figure 2 presents the conceptual framework of a typical meeting process, Figure 5 depicts its technical realization within a hybrid work environment.
+
+### 11.3 Speech recognition
+
+The speech recognition model, as defined in this Recommendation, performs voice signal processing and speaker speech-to-text conversion of meeting participants. It extracts acoustic and linguistic features from captured audio streams and transcribes spoken content into text to support speaker identification, real-time captioning, and meeting minutes generation within a hybrid meeting environment.
+
+### 11.4 Face recognition
+
+The face recognition model, as defined in this Recommendation, performs facial feature detection and identity verification of meeting participants. It extracts facial biometric data from captured images or video frames and matches them against pre-registered profiles to support speaker recognition, authentication, and attendance tracking within a hybrid meeting environment.
+
+### 11.5 Speaker identification
+
+The speaker recognition model, as defined in this Recommendation, identifies and distinguishes speakers from audio input in a hybrid meeting environment. It performs speaker segmentation, emotion recognition, and statistical extraction, producing outputs such as speaker-specific utterance data, emotional states, and quantitative participation metrics. The model supports accurate attribution of dialogue and enhances meeting analytics by combining biometric voice recognition and affective computing techniques. It extracts speech content, emotion recognition, and statistical information for each speaker.
+
+### 11.6 Question and dialogue processing
+
+The question and dialogue processing model, as defined in this Recommendation, performs semantic extraction and dialogue management functions based on [ITU-T F.746.3]. It analyses speech or textual inputs to derive meaning, intent, and context, enabling interactive communication and knowledge retrieval within a hybrid work environment. The model also supports adaptive dialogue flow by maintaining contextual consistency across multiple speakers and sessions.
+
+### 11.7 Emotion analysis
+
+Emotion analysis model, as defined in this Recommendation, analyses speech, text, and non-verbal cues to estimate the emotional state of the speaker at the time of presentation. The model employs acoustic and linguistic features such as pitch, tone, lexical sentiment, and prosody to determine emotional polarity and intensity. This information can be utilized to assess communication dynamics, contextual relevance, and overall engagement within hybrid meetings.
+
+### 11.8 Statistical analysis
+
+The statistical analysis model, as defined in this Recommendation, analyses quantitative indicators derived from speech and visual data to determine the level of participation and concentration of both speakers and listeners. The model applies time-based analysis of speech segments and non-verbal cues such as gaze and facial orientation to derive engagement metrics. It extracts the speaker's speech time and the degree of participation and concentration of the speaker and listener.
+
+### 11.9 Authentication
+
+Authentication model, as defined in this Recommendation, verifies the identity of participants through multimodal data and credential-based validation. Upon successful authentication, a unique identification code is generated and transmitted to the guest book for recording attendance information. This process ensures secure and traceable participation management in hybrid meetings. It extracts the participant's information that can be entered in the guestbook through the issuance of individual identifiers (IDs).
+
+### 11.10 Domain knowledge-based
+
+Domain knowledge-based model, as defined in this Recommendation, verifies the consistency and factual accuracy of meeting contents against a predefined domain knowledge base. The model performs semantic validation to determine whether the ongoing discussion corresponds to the meeting agenda and whether the statements made by speakers are supported by verifiable facts. It applies natural language understanding and entity-matching techniques within the knowledge base to maintain contextual coherence. It verifies whether the current meeting content is suitable for the domain and whether the speaker's content is based on facts.
+
+### 11.11 Guest book
+
+The guest book model, as defined in this Recommendation, manages the authenticated information of meeting participants. It receives identity data from the authentication model and maintains a structured participant record for attendance and access control purposes. The model transfers verified participant information to the *meeting minutes* component to support secure information delivery and role-based authorization. It extracts and delivers participant information to the meeting minutes through participant authentication.
+
+
+
+# SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.746.6-201712-I_PDF-E/raw.md

@@ -0,0 +1,455 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.746.6**
+
+(12/2017)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements for a name resolution service in  
+information-centric networks**
+
+Recommendation ITU-T F.746.6
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in blue, with "ITU" in a larger, bold font above it.
+
+ITU logo
+
+International  
+Telecommunication  
+Union
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+## **TELEGRAPH SERVICE**
+
+|                                                                 |             |
+|-----------------------------------------------------------------|-------------|
+| Operating methods for the international public telegram service | F.1–F.19    |
+| The gentex network                                              | F.20–F.29   |
+| Message switching                                               | F.30–F.39   |
+| The international telemessage service                           | F.40–F.58   |
+| The international telex service                                 | F.59–F.89   |
+| Statistics and publications on international telegraph services | F.90–F.99   |
+| Scheduled and leased communication services                     | F.100–F.104 |
+| Phototelegraph service                                          | F.105–F.109 |
+
+## **MOBILE SERVICE**
+
+|                                                        |             |
+|--------------------------------------------------------|-------------|
+| Mobile services and multdestination satellite services | F.110–F.159 |
+|--------------------------------------------------------|-------------|
+
+## **TELEMATIC SERVICES**
+
+|                                           |             |
+|-------------------------------------------|-------------|
+| Public facsimile service                  | F.160–F.199 |
+| Teletex service                           | F.200–F.299 |
+| Videotex service                          | F.300–F.349 |
+| General provisions for telematic services | F.350–F.399 |
+
+## **MESSAGE HANDLING SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.400–F.499 |
+|--|-------------|
+
+## **DIRECTORY SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.500–F.549 |
+|--|-------------|
+
+## **DOCUMENT COMMUNICATION**
+
+|                                      |             |
+|--------------------------------------|-------------|
+| Document communication               | F.550–F.579 |
+| Programming communication interfaces | F.580–F.599 |
+
+## **DATA TRANSMISSION SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.600–F.699 |
+|--|-------------|
+
+## **MULTIMEDIA SERVICES**
+
+|  |                    |
+|--|--------------------|
+|  | <b>F.700–F.799</b> |
+|--|--------------------|
+
+## **ISDN SERVICES**
+
+|  |             |
+|--|-------------|
+|  | F.800–F.849 |
+|--|-------------|
+
+## **UNIVERSAL PERSONAL TELECOMMUNICATION**
+
+|  |             |
+|--|-------------|
+|  | F.850–F.899 |
+|--|-------------|
+
+## **ACCESSIBILITY AND HUMAN FACTORS**
+
+|  |             |
+|--|-------------|
+|  | F.900–F.999 |
+|--|-------------|
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.746.6
+
+# Requirements for a name resolution service in information-centric networks
+
+## Summary
+
+Recommendation ITU-T F.746.6 describes the requirements for a flexible name resolution service in information-centric networks (ICN). It also describes the functional modules, i.e., name resolution service access control module, namespace management module, interoperation module and resolution engine module, of name resolution service in ICN. The name resolution service can support name resolution for any particular ICN instance independently. It also can facilitate interoperation between ICN instances with their own namespaces.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.746.6  | 2017-12-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/13428">11.1002/1000/13428</a> |
+
+## Keywords
+
+Information-centric networks, name resolution.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2018
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                          | Page |
+|----------------------------------------------------------------------------------------------------------|------|
+| 1 Scope.....                                                                                             | 1    |
+| 2 References.....                                                                                        | 1    |
+| 3 Definitions .....                                                                                      | 1    |
+| 3.1 Terms defined elsewhere .....                                                                        | 1    |
+| 3.2 Terms defined in this Recommendation.....                                                            | 2    |
+| 4 Abbreviations and acronyms .....                                                                       | 2    |
+| 5 Conventions .....                                                                                      | 2    |
+| 6 Motivation.....                                                                                        | 2    |
+| 7 Functional modules of name resolution service in ICN .....                                             | 3    |
+| 7.1 Name resolution service access control module.....                                                   | 3    |
+| 7.2 Namespace management module .....                                                                    | 3    |
+| 7.3 Interoperation module .....                                                                          | 4    |
+| 7.4 Resolution engine module .....                                                                       | 4    |
+| 8 Requirements for name resolution service in ICN .....                                                  | 4    |
+| 8.1 General requirements.....                                                                            | 4    |
+| 8.2 Requirements for NRS access control module .....                                                     | 4    |
+| 8.3 Requirements for namespace management module .....                                                   | 4    |
+| 8.4 Requirements for interoperation module.....                                                          | 4    |
+| 8.5 Requirements for resolution engine module.....                                                       | 5    |
+| 9 Security consideration .....                                                                           | 5    |
+| Annex A – Scenarios for name resolution services in ICN .....                                            | 6    |
+| A.1 Scenario of providing name resolution service for two ICN instances<br>independently .....           | 6    |
+| A.2 Scenario of providing name resolution service for interoperation between<br>two ICN instances.....   | 6    |
+| Appendix I – Survey of name resolution schemes used in Internet and information-centric<br>networks..... | 8    |
+| Bibliography.....                                                                                        | 9    |
+
+
+
+# Recommendation ITU-T F.746.6
+
+## Requirements for a name resolution service in information-centric networks
+
+## 1 Scope
+
+This Recommendation describes the requirements for a flexible name resolution service for information-centric networks (ICN). It defines the key functional modules for name resolution service in ICN. This Recommendation covers the following:
+
+- capabilities of name resolution service in ICN;
+- requirements for name resolution service in ICN;
+- scenarios of name resolution service for ICN instances.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T F.746.4] Recommendation ITU-T F.746.4 (2017), *Requirements for deployment of information-centric networks*.
+
+[ITU-T Y.3033] Recommendation ITU-T Y.3033 (2014), *Framework of data aware networking for future networks*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 future network (FN)** [b-ITU-T Y.3001]: A network able to provide services, capabilities, and facilities difficult to provide using existing network technologies. A future network is either:
+
+- a) A new component network or an enhanced version of an existing one, or
+- b) A heterogeneous collection of new component networks or of new and existing component networks that is operated as a single network.
+
+NOTE 1 – The plural form "Future Networks" (FNs) is used to show that there may be more than one network that fits the definition of a future network.
+
+NOTE 2 – A network of type b may also include networks of type a.
+
+NOTE 3 – The label assigned to the final federation may, or may not, include the word "future", depending on its nature relative to any preceding network and similarities thereto.
+
+NOTE 4 – The word "difficult" does not preclude some current technologies from being used in future networks.
+
+NOTE 5 – In the context of this Recommendation, the word "new" applied to a component network means that the component network is able to provide services, capabilities, and facilities that are difficult or impossible to provide using existing network technologies.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 name resolution:** The process by which, given an initial name and an initial naming context, an association between a name and the entity designated by the initial name can be found (adapted from [b-ITU-T X.902]).
+
+NOTE – The name resolution process does not necessarily provide sufficient information to interact with the designated entity.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                |
+|------|--------------------------------|
+| DNS  | Domain Name System             |
+| GNRS | Global Name Resolution Service |
+| GUID | Globally Unique Identifier     |
+| ICN  | Information-Centric Networks   |
+| NAT  | Network Address Translation    |
+| NDN  | Named Data Networking          |
+| NRS  | Name Resolution Service        |
+
+## 5 Conventions
+
+In this Recommendation:
+
+- The expression "**is required to**" indicates a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The expression "**is recommended**" indicates a requirement which is recommended but not absolutely required. Thus, this requirement need not be present to claim conformance.
+- The keywords "**can optionally**" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator / service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Motivation
+
+Information-centric networks (ICN) is a promising technology for future Internet design with which a user can directly obtain a content object by its name (or identification) without specifying the location of the content object. In recent years, various ICN solutions have been proposed with their own namespaces such as named data networking (NDN) [b-Jacobson], MobilityFirst [b-Seskar] and publish subscribe Internet technology (PURSUIT) [b-Fotiou].
+
+To identify different objects from their associated names, a name resolution service is needed. Different name resolution schemes are adopted for different ICN solutions, such as the rendezvous system in PURSUIT [b-Fotiou] and global name resolution service (GNRS) system in MobilityFirst [b-Seskar]. Various name resolution schemes differ from each other from the perspectives of resolution policies and management mechanisms. The comparison of resolution policies and management mechanisms among various existing name resolution schemes in the current Internet and ICN are shown in Table I.1 (see Appendix I).
+
+As described in [ITU-T F.746.4], each solution has its own pros and cons and is best suited to some particular application requirements. Different ICN service providers may deploy their own ICN instances with their own namespaces on top of the same physical network.
+
+To support the coexistence of various ICN instances on the same physical network, and to enable the potential interoperation among different ICN instances that employ different namespaces, a flexible name resolution service for information-centric networks is needed. This name resolution service provides dynamic resolution that allows the administrator of ICN instances to flexibly specify namespaces with their private naming schemes and resolution policies. Furthermore, this name resolution service is required to support any particular ICN instance independently, which means that internal-mapping relationships between multiple namespaces of the same ICN instance are maintained independently. It is also recommended that this name resolution service facilitate interoperation between different ICN instances with their own namespaces, which means the cross-mapping relationships between the multiple namespaces belonging to different ICN instances will be maintained.
+
+## 7 Functional modules of name resolution service in ICN
+
+As shown in Figure 7-1, the name resolution service in ICN includes four functional modules: name resolution service (NRS) access control module, namespace management module, resolution engine module and interoperation module. This clause addresses the capabilities of these functional modules.
+
+![Diagram of functional modules of name resolution service in ICN](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+The diagram illustrates the functional modules of the name resolution service in ICN. At the top, a box labeled 'Administrators of ICN instances' is connected to a central dashed box. Inside this dashed box, labeled 'Functional modules of name resolution service' on the right, are four modules: 'NRS access control module' at the top, 'Namespace management module' and 'Interoperation module' in the middle, and 'Resolution engine module' at the bottom. The 'NRS access control module' is connected to both the 'Administrators of ICN instances' and the 'Resolution engine module'. The 'Namespace management module' and 'Interoperation module' are connected to each other and to the 'Resolution engine module'. At the bottom, a box labeled 'Users of name resolution service' is connected to the 'Resolution engine module'. The diagram is labeled F.746.6(17)\_F7-1.
+
+Diagram of functional modules of name resolution service in ICN
+
+Figure 7-1 – Functional modules of name resolution service
+
+### 7.1 Name resolution service access control module
+
+The NRS access control module offers the capabilities of authentication and authorization. As there are multiple ICN instances coexisting in the same physical network, to safeguard the sensitive namespace information of each ICN instance, the administrators of the ICN instances must be authenticated and authorized to explore the capabilities provided by the namespace management module and interoperation module.
+
+### 7.2 Namespace management module
+
+The namespace management module is responsible for enabling the administrators of ICN instances flexibly to manage their own namespaces and specify their resolution policies. With this module, an administrator of the ICN instance can define namespaces with a particular naming scheme and indicate the scope of the namespace based on their design principles. The administrator can also create and update the names and the internal-mapping relationships between multiple namespaces of the same ICN instance.
+
+### **7.3 Interoperation module**
+
+An object has different names in different ICN instances. The interoperation module maintains the cross-mapping relationships between the multiple namespaces belonging to different ICN instances. The administrator of the ICN instance can indicate objects to which access by other ICN instance(s) is allowed. The interoperation modules of different ICN instances exchange with each other the names of the objects that can be accessed by other ICN instance(s).
+
+### **7.4 Resolution engine module**
+
+The resolution engine module uses the information and policies maintained in the namespace management module and interoperation module to accomplish the name resolution. When it receives the name resolution requests from NRS users, it queries the internal-mapping relationships provided by namespace management module and cross-mapping relationships provided by interoperation module in turn.
+
+## **8 Requirements for name resolution service in ICN**
+
+This clause addresses the requirements for name resolution service in ICN.
+
+### **8.1 General requirements**
+
+GEN-01: The name resolution service is required to support the name resolution for any particular ICN instance independently.
+
+GEN-02: The name resolution service is required to enable dynamic resolution such that the administrators of ICN instances can flexibly define their own namespace and resolution policies.
+
+GEN-03: The name resolution service is recommended to support interoperation between ICN instances.
+
+### **8.2 Requirements for NRS access control module**
+
+NA-01: The NRS access control module is required to authenticate the validity of the administrators of ICN instances that try to access and update the namespaces maintained by namespace management module.
+
+NA-02: The NRS access control module is required to authorize the administrators of ICN instances to explore the capabilities provided by the namespace management module and interoperation module.
+
+### **8.3 Requirements for namespace management module**
+
+NM-01: The namespace management module is required to enable the administrators of ICN instances to flexibly define their own namespaces with particular naming schemes and indicate the scope of the namespaces based on their design principles.
+
+NM-02: The namespace management module is required to allow the administrators of ICN instances to define their own resolution policies, such as where and how to conduct resolution, the used synchronization cycle, and the adopted algorithms.
+
+NM-03: The namespace management module is required to allow the administrator of an ICN instance to create and update the names and the internal-mapping relationships between multiple namespaces of the same ICN instance.
+
+### **8.4 Requirements for interoperation module**
+
+NI-01: The interoperation modules of ICN instances are recommended to exchange the names of the objects which are allowed to be accessed by other ICN instance(s).
+
+NI-02: The interoperation module is recommended to register the cross-mapping relationships between the multiple namespaces belonging to different ICN instances.
+
+NI-03: The interoperation module is recommended to unregister the cross-mapping relationships between the multiple namespaces belonging to different ICN instances.
+
+NI-04: The interoperation module is recommended to modify cross-mapping relationships between the multiple namespaces belonging to different ICN instances.
+
+### **8.5 Requirements for resolution engine module**
+
+NR-01: The resolution engine module is required to perform the name resolution using the information and policies maintained in the namespace management module and interoperation module.
+
+## **9 Security consideration**
+
+This Recommendation has similar security considerations to those pertinent to data aware networking and aligns with the security requirements specified in [ITU-T Y.3033].
+
+## Annex A
+
+## Scenarios for name resolution services in ICN
+
+(This annex forms an integral part of this Recommendation.)
+
+In ICN, data is requested and located by its name. To deliver the content by name, various name resolution schemes are employed by different ICN solutions. For example, PURSUIT employs a rendezvous system to mapping a content name, i.e., rendezvous identifier and service identifier, to a forwarding identifier. Each solution has its own pros and cons and is best suited to some particular application requirements. Different ICN service providers may deploy their own ICN instances with their own namespaces on top of the same physical network. A flexible name resolution service is needed to support ICN instance deployment. Two scenarios of name resolution service for ICN instances are illustrated, i.e., scenario of providing name resolution service for two ICN instances independently, and scenario of providing name resolution service for interoperation between two ICN instances.
+
+### A.1 Scenario of providing name resolution service for two ICN instances independently
+
+In this scenario, different ICN instances are deployed independently. As shown in Figure A.1, two different ICN instances are supported. There is no interoperation between them and the name resolution services for them are also independent. The interoperation modules are not used.
+
+![Diagram illustrating the scenario of supporting the name resolution for two ICN instances independently. The diagram shows two separate ICN instances, ICN instance 1 and ICN instance 2, each with its own administrators and a set of modules for name resolution. The modules include NRS access control, Namespace management, Interoperation (disabled), and Resolution engine. Each instance is connected to a cloud representing the network, which contains three nodes (routers) marked with a red 'X'.](08441fa90c5fd11994626f662ac13f19_img.jpg)
+
+The diagram illustrates two independent ICN instances. At the top, two boxes represent the 'Administrators of ICN instance 1' and 'Administrators of ICN instance 2'. Below each administrator box is a dashed rectangle containing four modules: 'NRS access control module', 'Namespace management module', 'Interoperation module' (indicated by a dashed border), and 'Resolution engine module'. Below each dashed rectangle is a cloud representing a network, containing three nodes (routers) marked with a red 'X'. Dashed lines connect the 'Resolution engine module' to each of the three nodes in its respective cloud. The clouds are labeled 'ICN instance 1' and 'ICN instance 2'. A small label 'F.746.6(17)\_FA.1' is located at the bottom right of the diagram.
+
+Diagram illustrating the scenario of supporting the name resolution for two ICN instances independently. The diagram shows two separate ICN instances, ICN instance 1 and ICN instance 2, each with its own administrators and a set of modules for name resolution. The modules include NRS access control, Namespace management, Interoperation (disabled), and Resolution engine. Each instance is connected to a cloud representing the network, which contains three nodes (routers) marked with a red 'X'.
+
+Figure A.1 – Scenario of supporting the name resolution for two ICN instances independently
+
+### A.2 Scenario of providing name resolution service for interoperation between two ICN instances
+
+As shown in Figure A.2, the administrators of these two ICN instances specify a set of objects that can be accessed from the other ICN instance. These cross-mapping relationships are maintained in the interoperation modules.
+
+![Diagram illustrating the scenario of interoperation between two ICN instances. Each instance has an administrator, an NRS access control module, a namespace management module, an interoperation module, and a resolution engine module. These modules are connected to a network of switches (represented by circles with red Xs) within the instance. The two instances are connected via a dashed line between their interoperation modules. The diagram is labeled F.746.6(17)_FA.2.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+The diagram shows two ICN instances, ICN instance 1 and ICN instance 2, connected via a dashed line between their interoperation modules. Each instance is managed by 'Administrators of ICN instance 1' or 'Administrators of ICN instance 2'. Below the administrators, each instance contains a set of modules: an 'NRS access control module', a 'Namespace management module', an 'Interoperation module', and a 'Resolution engine module'. These modules are connected to a network of switches (represented by circles with red Xs) within the instance. The interoperation module in each instance is connected to the resolution engine module and the namespace management module. The two interoperation modules are connected to each other via a dashed line. The switches in each instance are connected to the resolution engine module and the interoperation module. The diagram is labeled F.746.6(17)\_FA.2.
+
+Diagram illustrating the scenario of interoperation between two ICN instances. Each instance has an administrator, an NRS access control module, a namespace management module, an interoperation module, and a resolution engine module. These modules are connected to a network of switches (represented by circles with red Xs) within the instance. The two instances are connected via a dashed line between their interoperation modules. The diagram is labeled F.746.6(17)\_FA.2.
+
+**Figure A.2 – Scenario of interoperation between two ICN instances**
+
+When a host in ICN instance 1 wants to access an object in ICN instance 2, the resolution engine module finds the resolution results in the interoperation module and returns it to the requesting host. To support the interoperation between two ICN instances, the border switch needs to execute some procedures, e.g., packet translation and protocol adaption, as described in [ITU-T F.746.4]. In order to protect the border switch and guarantee that the message is not tampered with, the device that is responsible for name resolution chooses a trusted border switch. The resolution engine of the device generates a cipher text based on the name of the source host, the name of the destination host, and the identifier of the selected device (the selected border switch). The resolution engine module sends the cipher text to the source host. The source host then uses the cipher text to encapsulate the packets. The selected switch checks the validity of the packets from the source according to the information of the source host. The identifier of the selected switch and cipher text are then used to generate the verification information that is also included in the header of the packets before they are forwarded to the destination host. The cipher text and verification information will be used by the destination host to verify the received packets.
+
+## Appendix I
+
+### Survey of name resolution schemes used in Internet and information-centric networks
+
+(This appendix does not form an integral part of this Recommendation.)
+
+In the current Internet and ICN, various name resolution solutions are proposed. Each name resolution solution employs its own resolution policies and management methods as shown in Table I.1. A name resolution policy specifies how the names are resolved, including the type of resolution (e.g., one-way resolution, or two-way resolution) and the mapping relationship (e.g., one-to-one mapping or one-to-many mapping). The management mechanism is related to where the resolution procedures are performed (e.g., at individual routers or at dedicated servers), and how those nodes performing resolution are organized (e.g., in a distributed way, in a centralized way, or in a hierarchical way). These name resolution solutions employ their own resolution policies, which are static and lacks of flexibility to quickly provision efficient services.
+
+**Table I.1 – Existing name resolution solutions**
+
+| Project                                                     | Namespace                                                                     | Resolution policy                                         | Resolution management                                                                         |
+|-------------------------------------------------------------|-------------------------------------------------------------------------------|-----------------------------------------------------------|-----------------------------------------------------------------------------------------------|
+| Domain name system (DNS) [b-RFC 2136]                       | Domain name (global) → IP Address (global)                                    | One-way resolution<br>One-to-many mapping                 | Dedicated DNS server<br>Hierarchically organized                                              |
+| Network address translation (NAT) [b-RFC 2766]              | Private IP address + Port number ↔ Global IP address + Port number            | Bi-directional resolution<br>One-to-one mapping           | At a gateway                                                                                  |
+| MobilityFirst (Destination Resolution) [b-Seskar]           | (Globally unique identifier)<br>GUID → NA                                     | One-way resolution                                        | At distributed servers.<br>Dynamic updating and late binding.                                 |
+| Named data networking (NDN) [b-Jacobson]                    | Content name (global) → Interface identifier (local);                         | One-way resolution<br>One-to-many mapping                 | At individual router.<br>Pending Interest Table.<br>Distributed: Forwarding information base. |
+| eXpressive Internet architecture (XIA) (Routing) [b-Naylor] | XIA Identifier (global) → Interface identifier (local)                        | One-way resolution                                        | At router.                                                                                    |
+| PURSUIT (Content routing) [b-Fotiou]                        | Rendezvous identifier + Service identifier → Forwarding identifier (Regional) | One-way resolution<br>One-to-many mapping<br>Bloom filter | Dedicated server (Topology management)<br>Hierarchically organized                            |
+
+## Bibliography
+
+- [b-ITU-T X.902] Recommendation ITU-T X.902 (2009), *Information technology – Open Distributed Processing – Reference model: Foundations*.
+- [ITU-T Y.3001] Recommendation ITU-T Y.3001 (2011), *Future networks: Objectives and design goals*.
+- [b-RFC 2136] IETF RFC 2136 (1997), *Dynamic updates in the domain name system (DNS UPDATE)*.
+- [b-RFC 2766] IETF RFC 2766 (2000), *Network address translation-protocol translation (NAT-PT)*.
+- [b-Fotiou] N. Fotiou, D. Trossen, and G.C. Polyzos, *Illustrating a publish-subscribe internet architecture*, Telecommunication Systems, vol. 51, no. 4, pp. 233-245, 2012.
+- [b-Jacobson] V. Jacobson, D.K. Smetters, J.D. Thornton, M.F. Plass, N.H. Briggs, and R.L. Braynard, *Networking named content*, in Proc. of the 5th ACM CoNEXT, New York, USA, 2009, pp. 1-12.
+- [b-Naylor] Naylor D, Mukerjee M.K., Agyapong P, *et al.*, *XIA: architecting a more trustworthy and evolvable internet*, ACM SIGCOMM Computer Communication Review, 2014, 44(3): 50-57.
+- [b-Seskar] I.Seskar, K. Nagaraja, S. Nelson, and D. Raychaudhuri, *Mobility First future internet architecture project*, in Proc. of the 7th ACM AINTEC. New York, USA: ACM, 2011, pp. 1-3.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.747.10**
+
+(01/2022)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Requirements of distributed ledger systems  
+for secure human factor services**
+
+Recommendation ITU-T F.747.10
+
+ITU-T
+
+![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with a white grid pattern, overlaid by a stylized 'ITU' text in blue.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |             |
+|-----------------------------------------------------------------|-------------|
+| <b>TELEGRAPH SERVICE</b>                                        |             |
+| Operating methods for the international public telegram service | F.1–F.19    |
+| The gentex network                                              | F.20–F.29   |
+| Message switching                                               | F.30–F.39   |
+| The international telemessage service                           | F.40–F.58   |
+| The international telex service                                 | F.59–F.89   |
+| Statistics and publications on international telegraph services | F.90–F.99   |
+| Scheduled and leased communication services                     | F.100–F.104 |
+| Phototelegraph service                                          | F.105–F.109 |
+| <b>MOBILE SERVICE</b>                                           |             |
+| Mobile services and multdestination satellite services          | F.110–F.159 |
+| <b>TELEMATIC SERVICES</b>                                       |             |
+| Public facsimile service                                        | F.160–F.199 |
+| Teletex service                                                 | F.200–F.299 |
+| Videotex service                                                | F.300–F.349 |
+| General provisions for telematic services                       | F.350–F.399 |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499 |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549 |
+| <b>DOCUMENT COMMUNICATION</b>                                   |             |
+| Document communication                                          | F.550–F.579 |
+| Programming communication interfaces                            | F.580–F.599 |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699 |
+| <b>MULTIMEDIA SERVICES</b>                                      | F.700–F.799 |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849 |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899 |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999 |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.747.10
+
+# Requirements of distributed ledger systems for secure human factor services
+
+## Summary
+
+Recommendation ITU-T F.747.10 provides general requirements and functional capabilities for distributed ledger systems (DLS) for secure human factor services.
+
+This Recommendation describes the requirements for the secure human factor distributed ledger service model, which can solve conflicting goals of privacy protection and big personal human factor data utilization. This Recommendation also includes the functional capabilities for human factor distributed ledger shared nodes to perform machine learning without decryption on encrypted human factor data. However, the computational burden of machine learning for encrypted data may be excessive. To solve this problem, this human factor distributed ledger service model provides procedures for allowing the use of two or more encryption key pairs and notifying the key type. In addition, this Recommendation involves the integrity maintaining requirements for secure human factor services to maintain a safe distributed ledger and, checked from the beginning, to distribute personal human factor information. Therefore, the application of distributed ledger system in the distribution of personal secure human factor information can ensure transparent tracking from the distribution process to the final use path.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.747.10 | 2022-01-17 | 16          | <a href="http://handle.itu.int/11.1002/1000/14644">11.1002/1000/14644</a> |
+
+## Keywords
+
+Distributed ledger service model, privacy protection expansion, secure human factor, transparency tracking.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2022
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                                  | Page |
+|------------------------------------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                                                    | 1    |
+| 2 References.....                                                                                                | 1    |
+| 3 Definitions .....                                                                                              | 1    |
+| 3.1 Terms defined elsewhere .....                                                                                | 1    |
+| 3.2 Terms defined in this Recommendation.....                                                                    | 2    |
+| 4 Abbreviations and acronyms .....                                                                               | 2    |
+| 5 Conventions .....                                                                                              | 2    |
+| 6 Background.....                                                                                                | 3    |
+| 7 General requirements for distributed ledger systems of secure human factor services                            | 3    |
+| 7.1 Functional requirements for public distributed ledger shared nodes.....                                      | 4    |
+| 7.2 Authentication requirements for new participating node .....                                                 | 4    |
+| 7.3 Security requirements for distributed ledger system .....                                                    | 5    |
+| 7.4 Integrity maintaining requirements for a distributed ledger system.....                                      | 5    |
+| 8 Functional capabilities for distributed ledger systems of secure human factor services .....                   | 6    |
+| 8.1 Distributed ledger structure in distribution of personal human factor information .....                      | 6    |
+| 8.2 Two functions in distributed ledger structure in the distribution of personal human factor information ..... | 6    |
+| 8.3 Distributed ledger system maintenance methodologies .....                                                    | 7    |
+| Annex A – Application to secure human factor distributed ledger service model .....                              | 9    |
+| Bibliography.....                                                                                                | 10   |
+
+
+
+# Recommendation ITU-T F.747.10
+
+## Requirements of distributed ledger systems for secure human factor services
+
+# 1 Scope
+
+This Recommendation describes requirements for distributed ledger systems (DLS) for secure human factor services, covering:
+
+- Background;
+- General requirements for DLS for secure human factor services;
+- Functional capabilities for DLS for secure human factor services.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+- 3.1.1 block** [b-ISO 22739]: Structured data comprising block data and a block header.
+- 3.1.2 consensus** [b-ISO 22739]: Agreement among DLT nodes that 1) a transaction is validated and 2) that the distributed ledger contains a consistent set and ordering of validated transactions.
+- 3.1.3 digital signature** [b-ISO 22739]: Data which, when appended to a digital object, enable the user of the digital object to authenticate its origin and integrity.
+- 3.1.4 distributed ledger** [b-ISO 22739]: Ledger that is shared across a set of DLT nodes and synchronized between the DLT nodes using a consensus mechanism.
+- 3.1.5 distributed ledger technology** [b-ISO 22739]: Technology that enables the operation and use of distributed ledgers.
+- 3.1.6 fork** [b-ITU-T TS FG DLT D1.1]: Creation of two or more different versions of a distributed ledger.
+- 3.1.7 hash value** [b-ISO 22739]: String of bits which is the output of a cryptographic hash function.
+- 3.1.8 health** [b-WHO]: A state of physical, mental and social well-being in which disease and infirmity are absent.
+- 3.1.9 ledger** [b-ISO 22739]: Information store that keeps records of transactions that are intended to be final, definitive and immutable.
+- 3.1.10 Merkle tree** [b-NIST]: A data structure where the data is hashed and combined until there is a singular root hash that represents the entire data structure.
+
+- 3.1.11 mining** [b-ITU-T F.751.0]: A reward-seeking activity in some consensus mechanisms.
+- 3.1.12 node** [b-ISO 22739]: Elementary component from which a data structure is built.
+- 3.1.13 public distributed ledger system** [b-ITU-T F.751.0]: DLT system which is accessible to the public for use.
+- 3.1.14 transaction** [b-ISO 22739]: Smallest unit of a work process, which is one or more sequences of actions required to produce an outcome that complies with governing rules.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+- 3.2.1 block depth**: The level of a block appended to the distributed ledger system chain from its the initial block.
+- 3.2.2 electronic human factor records**: The systematized collection of person and population electronically stored human factor information in a digital format.
+- 3.2.3 human factor**: Principles to the design of optimal life-style conditions with regard to human well-being, safety and health, including the development of existing technologies and the acquisition of new ones.
+- NOTE – Adapted from [b-ISO 6385] and [b-Wickens].
+- 3.2.4 personal human factor information**: The information collected by directly measuring the human body and its environments and which is transmitted to personal human factor devices or other devices through a communication network to be used for electronic human factor records.
+- 3.2.5 personal human factor device**: A type of device that measures the human body and its environments, and exchanges information collected with other human factor devices.
+- 3.2.6 secure human factor**: The human factor in information security.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                   |
+|------|-----------------------------------|
+| CPU  | Central Processing Unit           |
+| DLS  | Distributed Ledger Systems        |
+| DLT  | Distributed Ledger Technology     |
+| IP   | Internet Protocol                 |
+| PDLS | Public Distributed Ledger Systems |
+| UUID | Universally Unique Identifier     |
+| VRF  | Verifiable Random Function        |
+
+## **5 Conventions**
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+- The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator or service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with this Recommendation.
+
+## 6 Background
+
+In recent years, personal human factor information has increased dramatically due to the development of personal health collection devices as well as hospital-based personal medical record data. One of the best models for the management and sharing of personal human factor data is the distributed ledger service model. The characteristics of the distributed ledger systems provide reliability using a distributed database with multiple nodes involved, and ensure transparency of the retrieval data using digital signatures and hash values. However, human factor data can be very sensitive in terms of information protection. Therefore, the public distributed ledger service model requires personal human factor information protection requirements (see Figure 1).
+
+![Figure 1 – Human factor distributed ledger service model diagram](b3baf3a29b67c7425d2562ddbc52f0cc_img.jpg)
+
+The diagram illustrates the Human factor distributed ledger service model across three horizontal layers. The top layer, labeled 'Applications', contains five orange rectangular boxes: 'Personal human factor record', 'Electronic health record', 'Clinic trial', 'Well-being and safety management', and 'Person identification'. The middle layer, labeled 'Users', features seven icons representing different user groups: a person, a hospital, a person presenting to others, a building, a smartphone, a person in a wheelchair, and a classical building. The bottom layer, labeled 'Network', is a single green rectangular bar labeled 'PDLS: Public distributed ledger systems'. The text 'F.747.10(22)' is located in the bottom right corner of the diagram area.
+
+Figure 1 – Human factor distributed ledger service model diagram
+
+**Figure 1 – Human factor distributed ledger service model**
+
+This Recommendation describes the security requirements of the human factor distributed ledger service model, which can achieve goals of privacy protection and personal health big data utilization. The Recommendation also introduces the functional requirements of distributed ledger shared nodes to perform machine learning without decryption on encrypted data. It describes the incentive requirements in the distributed ledger service model to improve the quality of life by automating the distribution of health products directly to consumers and producers. The application of distributed ledger technology starts with the ability to track and manage health information production and distribution. In other words, the application of distributed ledger technology in the distribution of personal human factor information can ensure transparent tracking from the distribution process to the final use path. For this reason, individuals represented by individual nodes participating in the distributed ledger system can trust and use the information distributed. In addition, it is possible to provide a method for fundamentally blocking illegal distribution of personal human factor information.
+
+# 7 General requirements for distributed ledger systems of secure human factor services
+
+This clause describes the requirements for a secure distributed ledger movement management procedure that can achieve the conflicting goals of personal information protection and the use of personal human factor information big data. It introduces the functional requirements of a distributed ledger shared node to perform machine learning without decryption on encrypted data. For example, homomorphic encryption is a cryptographic technique that can perform all computations performed by a computer without decryption even in an encrypted state. Even in data analysis including personal information to be protected, machine learning can be optionally performed without personal information leakage or data loss.
+
+## 7.1 Functional requirements for public distributed ledger shared nodes
+
+The following are the functional requirements for public distributed ledger shared nodes:
+
+- Nodes are required to store the data of the distributed ledger chain accumulated from the first block.
+- The completion status is required to be delivered to the other nodes, as a node executes a distributed confirmation algorithm, when the transaction is verified.
+- In order to verify the validity of the distributed ledger generated at each round, the node is required to check the validity of the generated block by comparing it with the target hash value.
+- Each node is required to update and maintain shared data such as the public key list of all other nodes and the distributed ledger.
+- The node is required to propagate the transaction to other nodes until the agreement phase (e.g., transaction confirmation completion) in the transaction verification process.
+- The node is required to encrypt data of a transaction that requires security using the cryptographic keys (e.g., public key certificate [b-ITU-T X.509], homomorphic encryption [b-ISO 18033-6], verifiable random function (VRF) [b-IETF draft-irtf-cfrg-vrf-08] and inform the encryption key type.
+- The node is required to determine whether the decryption is necessary. If the decryption is needed, it decrypts and transmits it to the requesting node. If there is no decryption needed, the node encrypts it with the public key of the request node, and transmits it.
+
+## 7.2 Authentication requirements for new participating node
+
+Existing nodes are recommended to provide the functions outlined in clauses 7.2.1 to 7.2.3, to authenticate new participating nodes in a distributed ledger shared system.
+
+### 7.2.1 Requirements for requesting new node authentication
+
+- The new node is recommended to have at least two pairs of encryption keys to use (e.g., public key certificate [b-ITU-T X.509], homogeneous encryption keys [b-ISO 18033-6] before making a request.
+- The new node is recommended to encrypt the request message with its own private key and to send the encrypted data and its public key together to the node.
+- Each node is recommended to update the list of verified public keys of the new and existing nodes and to store the public key list of the distributed ledger shared system to participate, when the node verifies and transmits the authenticated information.
+
+### 7.2.2 Authentication functional requirements for the node
+
+- The node is recommended to verify the validity by decrypting the encrypted data transmitted from the new participation desired node received together with the public key, to encrypt the verified information and the public key list with the public key of the new node and transmits the encrypted information.
+- The node is recommended to be a list of public keys of all the nodes participating in the distributed ledger shared system and update its corresponding public key list each time it handles authentication of the new node.
+- Each time the node is recommended to update its public key list, it is required to encrypt the public key list with its own private key and send it to all nodes participating in the distributed ledger shared system.
+
+- The node is recommended to permanently store the verified information about the nodes participating in the distributed ledger shared system together with the verification time and the address of the participating node.
+
+### **7.2.3 Requirements for new node authentication verification of existing nodes**
+
+- Existing nodes are recommended to verify the digital signature of the public key list sent by the node and to update it with the new public key list.
+- Existing nodes are recommended to verify the participation of the authenticated new node by checking the new public key list.
+
+## **7.3 Security requirements for distributed ledger system**
+
+Existing nodes are recommended to follow the provisions in this clause.
+
+- Attempts to manipulate information in an existing shared distributed ledger are required to be verified using an electronic signature and rejected in the distributed ledger.
+- Among the main chains used in the distributed ledger system, chains with different contents from the longest chain before an arbitrary b-block depth at the time a new block is created are required to be rejected in the distributed ledger. Here b is a number larger than equal to 1.
+- The data is required to be rejected in the process of creating the distributed ledger, when data with duplicate addresses (e.g., IP, UUID) are added to the distributed ledger system.
+- It is required that the common random source (e.g., cryptographic nonce [b-NIST]) be the same for blocks of any d-block depth. Blocks after d-block depth are required to update the common random source by a g-block depth. When updated, the hash of the newly added block is recommended to be used as a random source.
+
+NOTE – Here d-block and g-block depth means any blocks with depth larger than 1.
+
+- Chains containing blocks with different hash values of previous blocks and Merkle tree root values are required to be rejected in the distributed ledger.
+- If an error node occurs amongst the constituent nodes of the distributed ledger system, the nodes without errors are recommended to be maintained if above the pre-defined consensus level for the DLS.
+
+## **7.4 Integrity maintaining requirements for a distributed ledger system**
+
+Existing nodes are recommended to follow the provisions in this clause.
+
+- Each node is recommended to eliminate an attempt to manipulate information in the existing shared distributed ledger. If such an attack is detected, the number of nodes is recommended to be accumulated to obtain the ratio of the hashing force. It is recommended to compare the current number of block trees with the value of the threshold value to calculate safety and transmit (broadcast) related information and node addresses to all nodes.
+- Each node is recommended to remove the longest chains commonly used in the distributed ledger system and chains with different contents from the distributed ledger system.
+- Each node is recommended to remove the chain containing blocks with different hash values or Merkle tree root values of the previous blocks in the distributed ledger and calculate the accumulated number of nodes that were subject to attacks to determine whether the distributed ledger is safe, and to transmit (broadcast) the relevant information and the address of the node.
+
+- When an error or forgery node occurs among the components of the distributed ledger system, each node is recommended to remove and accumulate the number of nodes attempted to perform an error or attack to obtain a hashing power ratio. In the distributed ledger, the number of secure nodes is recommended to be maintained to be greater than the threshold value and related information and node addresses are recommended to be transmitted (broadcast).
+- Each node is recommended to reject the data in the distributed ledger creation process when new data with duplicate addresses is added to the data of the distributed ledger system.
+
+# 8 Functional capabilities for distributed ledger systems of secure human factor services
+
+As an incentive, it is required to improve the quality of life in a distributed ledger service model by automating direct distribution of personal human factor information. The application of distributed ledger technology starts with the ability to track and manage human factor information production and distribution. In other words, the application of distributed ledger technology in the distribution of personal human factor information can ensure transparent tracking from the distribution process to the final use path. For this reason, individuals represented by individual nodes participating in the distributed ledger system can trust and use the information distributed. In addition, it is possible to provide a method for fundamentally blocking illegal distribution of personal human factor information.
+
+## 8.1 Distributed ledger structure in distribution of personal human factor information
+
+Following the convention, the first transaction of the ledger is a special transaction that starts a new incentive (e.g., virtual coins [b-ITU-T F.751.0]) that will be disbursed to the creator of the ledger. This incentive is rewarded to nodes to maintain a distributed ledger and distributed from the beginning to distribute personal human factor information. The techniques for providing and distributing these incentives are recommended to be agreed in advance because they operate as distributed systems. The reason to continually add a certain number of new incentives is the compensation for nodes (miners) that consume resources to operate the distributed ledger system. These nodes consume central processing unit (CPU) computational power, memory and coins.
+
+## 8.2 Two functions in distributed ledger structure in the distribution of personal human factor information
+
+As a method to reduce the waiting time while increasing the mining speed, a technique of decomposing the structure of the basic distributed ledger into three functions can be optionally used. This can be seen as selecting the main chain in the distributed ledger protocol (e.g., the longest chain selection technique), which leads to the selection of the secure ledger among all ledgers at each depth of the ledger tree. Here, the depth of a ledger is defined as the distance from the origin ledger (the number of connected blocks in the ledger).
+
+In a distributed ledger, the ledger serves three purposes. That is, it serves to elect the captain, add transactions to the main chain, and vote for the ancestor ledger through parent link relationships. In expressing the ledger as a conceptual action, it is divided into two functions (see Figure 2). The proposal function bundles transactions of the same depth in the original ledger tree. The voting function selects the ledger part of the ledger by voting for the same depth of transactions in the ledger tree. The selected ledger takes the partial ledgers of the transactions and forms the final ledger. This voting function operates at the same depth of the ledger tree and creates a parent-child connection. Therefore, the parent-child link of the original ledger tree has two functions that are explicitly separated: 1) Providing some order of ledgers in the transaction part at the same depth, 2) the voting function which helps to vote for each other to screen the ledger. The overall structure of the distributed ledger for the distribution of personal human factor information described below is shown in Figure 2.
+
+Due to the distributed nature of DLS, it faces stability problems. In DLS, each node can record a transaction, but in the end, which node is selected is a result of the consensus algorithm [b-ITU-T F.751.0]. The design of a DLS is required to be taken into consideration as one of the many factors affecting stability, and the distributed ledger is recommended to recover stable service through adaptive processing of the system. In order to solve the stability problem of DLS, the common random source (e.g., cryptographic nonce [b-NIST]) is kept the same for d-block depths, and blocks after d-depths should update the common random source by g-block depths. When updated, the hash of the newly added block is used as a random source. If  $d = 1$ , it is restored to the basic update rule that forks every epoch, most vulnerable to contamination (balanced) attacks. In order to normally increase the security threshold,  $d$  may be increased. When  $d = \infty$ , all blocks use the nonce of the origin block as a common random source. This is the longest chain protocol that does not allow forking, allowing for private prediction of the chain by the contaminated owner of the secret key.
+
+![Figure 2 – Distributed ledger service model structure. The diagram illustrates a hierarchical tree of blocks. Each block is a rectangle containing three blue circles, representing a 'Block (Proposal and voting function)' with 'Transactions'. Solid arrows represent 'Parent-child links' between blocks. Dashed lines connect blocks horizontally at the same level. On the right, two vertical double-headed arrows indicate 'd-block depth: fork delay' for the top three levels and 'g-block depth: fork allowed' for the subsequent levels. A legend at the bottom identifies the block icon, the parent-child link arrow, and the transaction circle. The code 'F.747.10(22)' is in the bottom right corner.](4e4be0bd8b235167902f2c03e41da651_img.jpg)
+
+Figure 2 – Distributed ledger service model structure. The diagram illustrates a hierarchical tree of blocks. Each block is a rectangle containing three blue circles, representing a 'Block (Proposal and voting function)' with 'Transactions'. Solid arrows represent 'Parent-child links' between blocks. Dashed lines connect blocks horizontally at the same level. On the right, two vertical double-headed arrows indicate 'd-block depth: fork delay' for the top three levels and 'g-block depth: fork allowed' for the subsequent levels. A legend at the bottom identifies the block icon, the parent-child link arrow, and the transaction circle. The code 'F.747.10(22)' is in the bottom right corner.
+
+**Figure 2 – Distributed ledger service model structure**
+
+## 8.3 Distributed ledger system maintenance methodologies
+
+This representation of functional separation of a distributed ledger is much more complicated than that of a traditional distributed ledger, but it can improve the performance of the distributed ledger by deriving a faster consensus. This quick consensus deriving function can increase the number of ledgers in the transaction part without compromising the security of the distributed ledger in the proposed function. Therefore, the number of ledgers will be limited only by the capacity of the underlying communication network. The consensus can be optionally confirmed with low latency and high reliability since the voting function of multiple transactions will be voted in parallel to the ledger of the proposal for quick confirmation. The personal human factor information distributed ledger system is easy to manage because the general ledger generation rate has increased tremendously, and the number of partial ledgers of the proposed function per depth can be small.
+
+This distributed ledger system can compromise transparency by concentrating the power of hashing into the proposed function of a specific transaction in the process of selecting the ledger. As shown in Figure 3, if an attacker's hashing power is strong in a specific ledger of the proposed function, it can be very vulnerable to security. Figure 3 shows an example of a chain of ledgers being destroyed
+
+or contaminated by the concentration of the hashing power of an attacker. If an attacker were able to gather more CPU computational power, memory, and coins in one place than all secure nodes, the attacker would have to decide whether to use it to steal honest node incentives or use it to cooperate. It would be necessary to provide an incentive policy so that it would be more beneficial for an attacker to follow the rules than to undermine the transparency of the personal human factor information distributed ledger system. This incentive is required to be adjusted to be distributed across participating nodes. The attacker can provide such a rule that it would be more profitable to associate with all other nodes. This rule is recommended to keep the number of honest nodes above the threshold value (e.g.,  $CD (1 + \alpha)/(\alpha-1)/\log(\alpha)$ ) according to the ratio of the hashing force of the attacker ( $\alpha$ ). Here C and D are capacity and delay of communication networks.
+
+What can be seen from this formula is that if  $\alpha$  is close to 0, the attacker's hashing power is weak, it can be said that there is no problem in the security of distributed ledger systems even if the number of the voter block-tree is a small number. However, if  $\alpha$  is close to 1, that is, if the attacker's hashing power is strong, the number of the voter block-tree should be increased exponentially. At this point, it can be observed that it becomes very vulnerable to security.
+
+![Diagram illustrating pollution prevention in a distributed ledger service model. The diagram shows a tree of blocks, with honest blocks in white and attacker's proposal blocks in red. The diagram is divided into two sections: 'd-block depth: fork delay' and 'g-block depth: fork allowed'. A legend at the bottom defines the symbols: a white rectangle for 'Block (Proposal and voting function)', a blue arrow for 'Parent-child link', a blue circle for 'Transaction', and a red rectangle for 'Attacker's proposal block'. The reference code F.747.10(22) is shown at the bottom right.](4ee27dbf5ef12e7b58b0ef0937bc5a5e_img.jpg)
+
+The diagram illustrates a block tree structure. At the top, there are three white blocks connected vertically by blue arrows (parent-child links). Each block contains three blue circles (transactions). A dashed vertical line separates the top section from the bottom section. The top section is labeled 'd-block depth: fork delay' and contains three white blocks. The bottom section is labeled 'g-block depth: fork allowed' and contains five white blocks and one red block (attacker's proposal block). The red block is connected to one of the white blocks in the top section. The legend at the bottom shows a white rectangle for 'Block (Proposal and voting function)', a blue arrow for 'Parent-child link', a blue circle for 'Transaction', and a red rectangle for 'Attacker's proposal block'. The reference code F.747.10(22) is shown at the bottom right.
+
+Diagram illustrating pollution prevention in a distributed ledger service model. The diagram shows a tree of blocks, with honest blocks in white and attacker's proposal blocks in red. The diagram is divided into two sections: 'd-block depth: fork delay' and 'g-block depth: fork allowed'. A legend at the bottom defines the symbols: a white rectangle for 'Block (Proposal and voting function)', a blue arrow for 'Parent-child link', a blue circle for 'Transaction', and a red rectangle for 'Attacker's proposal block'. The reference code F.747.10(22) is shown at the bottom right.
+
+**Figure 3 – Example of pollution prevention in distributed ledger service model**
+
+In the process of selecting the proposal block, the function of the block is recommended to be determined by adjusting the power of hashing and coins. At this time, it can be seen that if the attacker's hashing power and coins is strong, the security is very vulnerable. If an attacker could gather more computational power and coins than all honest nodes, a decision would need to be taken whether to use it to steal the benefits of an honest node, or to use it to cooperate. Incentive policies are recommended to be provided so that it would be more beneficial for attackers to adhere to the rules than to undermine the system and the legitimacy of their own wealth. Using a policy that prevents profits from being concentrated on a specific proponent block, this is recommended to involve providing such a rule that attackers would benefit more from allocating with all other nodes.
+
+## Annex A
+
+### Application to secure human factor distributed ledger service model
+
+(This annex forms an integral part of this Recommendation.)
+
+The distributed ledger scenario shown in Figure A.1 can safely and transparently manage not only hospital-centred personal human factor data, but also personal-centred human factor data such as personal health collection devices. In the example of using personal health information sharing in Figure A.1, reliability can be provided by using a distributed ledger in which multiple nodes participate, and digital signatures and hash values can be used to ensure transparency in search data. However, personal human factor data can be very sensitive in terms of data protection. Such sensitive data is registered in an encrypted state using an encryption technique capable of processing big data. The mobility procedure for sensitive personal human factor information follows the requirements and procedures of the distributed ledger shared system in clause 7.2 using an encryption algorithm (see Figure A.1). In addition, the distributed ledger system for personal human factor information is required to be operated to satisfy the requirements for the incentive function in clause 8.3 for activation and maintenance.
+
+![Diagram of Figure A.1 showing the secure distributed ledger service model. It illustrates the interaction between various entities (Enterprise, Hospital, Government, School/Research centre) and a public distributed ledger system. The diagram shows a network of nodes (smartphones) where a new node joins and is authenticated by existing nodes. It depicts a patient requesting encrypted data registration and a doctor requesting safe access using isomorphic encryption. A central server manages the incentive distribution policy. The system relies on 'enough honest nodes' for safety.](75f0cb39f1cd165dfe4a6aa6c4d9388d_img.jpg)
+
+Enterprise
+Hospital
+Government
+School/Research centre
+
+Safe sharing of personal human factor information
+
+New node
+Existing nodes
+Existing node (Authenticating)
+Encrypted personal human factor information registration request
+Distributed ledger requires authentication
+Incentive distribution policy
+Request for safe access to personal human factor information using isomorphic encryption techniques, etc.
+Enough honest nodes
+
+Safety for personal human factor information in public distributed ledger system
+
+F.747.10(22)
+
+Diagram of Figure A.1 showing the secure distributed ledger service model. It illustrates the interaction between various entities (Enterprise, Hospital, Government, School/Research centre) and a public distributed ledger system. The diagram shows a network of nodes (smartphones) where a new node joins and is authenticated by existing nodes. It depicts a patient requesting encrypted data registration and a doctor requesting safe access using isomorphic encryption. A central server manages the incentive distribution policy. The system relies on 'enough honest nodes' for safety.
+
+**Figure A.1 – Scenarios for secure distributed ledger service model**
+
+## Bibliography
+
+- [b-ITU-T F.751.0] Recommendation ITU-T F.751.0 (2020), *Requirements for distributed ledger systems*.
+- [b-ITU-T X.509] Recommendation ITU-T X.509 (2019) | ISO/IEC 9594-8:2020, *Information technology – Open Systems Interconnection – The Directory: Public-key and attribute certificate frameworks*.
+- [b-ITU-T TS FG DLT D1.1] Technical Specification ITU-T FG DLT D1.1 (2019), *Distributed ledger technology terms and definitions*.
+- [b-IETF draft-irtf-cfrg-vrf-08] IETF draft-irtf-cfrg-vrf-08 (2020), *Verifiable Random Functions (VRFs)*. <https://tools.ietf.org/html/draft-irtf-cfrg-vrf-08>
+- [b-ISO 6385] ISO 6385:2016, *Ergonomics principles in the design of work systems*.
+- [b-ISO 18033-6] ISO 18033-6:2019, *IT Security techniques – Encryption algorithms – Part 6: Homomorphic encryption*.
+- [b-ISO 22739] ISO 22739:2020, *Blockchain and distributed ledger technologies – Vocabulary*.
+- [b-NIST] NISTIR 8202 (2018). *Blockchain Technology Overview*.
+- [b-WHO] World Health Organization (2006), *Constitution of the World Health Organization – Basic Documents*, Forty-fifth edition, Supplement.
+- [b-Wickens] Wickens, D., Gordon, S., Liu, Y. (1997), *An Introduction to Human Factors Engineering*. pp.2-7. New York, NY: Longman.
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+# Recommendation **ITU-T F.747.12 (12/2022)**
+
+SERIES F: Non-telephone telecommunication services  
+Multimedia services
+
+---
+
+## **Requirements for artificial intelligence based machine vision system in smart logistics warehouse**
+
+![ITU logo](390120de4fe440c42fea8154fcaad334_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+### **TELEGRAPH SERVICE**
+
+|                                                                 |             |
+|-----------------------------------------------------------------|-------------|
+| Operating methods for the international public telegram service | F.1–F.19    |
+| The gentex network                                              | F.20–F.29   |
+| Message switching                                               | F.30–F.39   |
+| The international telemessage service                           | F.40–F.58   |
+| The international telex service                                 | F.59–F.89   |
+| Statistics and publications on international telegraph services | F.90–F.99   |
+| Scheduled and leased communication services                     | F.100–F.104 |
+| Phototelegraph service                                          | F.105–F.109 |
+
+### **MOBILE SERVICE**
+
+|                                                        |             |
+|--------------------------------------------------------|-------------|
+| Mobile services and multdestination satellite services | F.110–F.159 |
+|--------------------------------------------------------|-------------|
+
+### **TELEMATIC SERVICES**
+
+|                                           |             |
+|-------------------------------------------|-------------|
+| Public facsimile service                  | F.160–F.199 |
+| Teletex service                           | F.200–F.299 |
+| Videotex service                          | F.300–F.349 |
+| General provisions for telematic services | F.350–F.399 |
+
+### **MESSAGE HANDLING SERVICES**
+
+F.400–F.499
+
+### **DIRECTORY SERVICES**
+
+F.500–F.549
+
+### **DOCUMENT COMMUNICATION**
+
+|                                      |             |
+|--------------------------------------|-------------|
+| Document communication               | F.550–F.579 |
+| Programming communication interfaces | F.580–F.599 |
+
+### **DATA TRANSMISSION SERVICES**
+
+F.600–F.699
+
+### **MULTIMEDIA SERVICES**
+
+**F.700–F.799**
+
+## **ISDN SERVICES**
+
+F.800–F.849
+
+## **UNIVERSAL PERSONAL TELECOMMUNICATION**
+
+F.850–F.899
+
+## **ACCESSIBILITY AND HUMAN FACTORS**
+
+F.900–F.999
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.747.12
+
+# Requirements for artificial intelligence based machine vision system in smart logistics warehouse
+
+## Summary
+
+With the rapid development of industrial automation and logistics technology in accordance with the market demand for high-tech, machine vision technology has begun to enable the automation transformation of logistics warehouse systems. The application of machine vision technology in the field of logistics warehouse has enabled the rapid evolution of goods sorting, goods palletizing and de-palletizing, goods handling and shelf inventory from intensive manual work to intelligence and automation, improving the operational efficiency and management capabilities of logistics warehouse.
+
+Recommendation ITU-T F.747.12 specifies the requirements and framework for artificial intelligence based machine vision system in smart logistics warehouse, and provides use cases. This Recommendation is intended to guide the design and development of machine vision systems in smart logistics warehouse.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.747.12 | 2022-12-14 | 16          | <a href="http://handle.itu.int/11.1002/1000/15193">11.1002/1000/15193</a> |
+
+## Keywords
+
+Artificial intelligence, framework, machine vision system, requirements, smart logistics warehouse.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                                   | Page |
+|-------------------------------------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                                                     | 1    |
+| 2 References.....                                                                                                 | 1    |
+| 3 Definitions .....                                                                                               | 1    |
+| 3.1 Terms defined elsewhere .....                                                                                 | 1    |
+| 3.2 Terms defined in this Recommendation.....                                                                     | 1    |
+| 4 Abbreviations and acronyms .....                                                                                | 2    |
+| 5 Conventions .....                                                                                               | 2    |
+| 6 Overview .....                                                                                                  | 2    |
+| 7 Framework.....                                                                                                  | 2    |
+| 8 Requirements .....                                                                                              | 3    |
+| 8.1 Device requirements .....                                                                                     | 3    |
+| 8.2 Service requirements .....                                                                                    | 4    |
+| 8.3 Application requirements .....                                                                                | 6    |
+| Appendix I – Use cases of artificial intelligence based machine vision system in a smart logistics warehouse..... | 8    |
+| I.1 Goods sorting.....                                                                                            | 8    |
+| I.2 Goods palletizing and de-palletizing.....                                                                     | 8    |
+| I.3 Shelf inventory .....                                                                                         | 8    |
+| I.4 Goods handling.....                                                                                           | 9    |
+| I.5 Logistics warehouse environment monitoring .....                                                              | 9    |
+| Bibliography.....                                                                                                 | 10   |
+
+
+
+# Recommendation ITU-T F.747.12
+
+## Requirements for artificial intelligence based machine vision system in smart logistics warehouse
+
+## 1 Scope
+
+This Recommendation specifies requirements and framework for artificial intelligence (AI) based machine vision systems (MVSs) in a smart logistics warehouse (SLW).
+
+The scope of this Recommendation includes:
+
+- overview of AI based MVS in SLW;
+- framework of AI based MVS in SLW;
+- requirements of AI based MVS in SLW.
+
+Use cases of AI based MVS in SLW are provided in Appendix I.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T H.627] Recommendation ITU-T H.627 (2020), *Signalling and protocols for a video surveillance system*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 accuracy** [b-ISO/IEC 2382]: Qualitative measure of the magnitude of error, preferably expressed as a function of the relative error, a high value of this measure corresponding to a small error.
+
+**3.1.2 algorithm** [b-ISO/IEC 11557]: A set of rules for transforming the logical representation of data.
+
+**3.1.3 machine vision** [b-ITU-T F.748.16]: Signal processing to acquire, process and interpret an image or video to support visual analysis for applications, such as automatic inspection, process control and guidance.
+
+### 3.2 Terms defined in this Recommendation
+
+None.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                               |
+|-----|-------------------------------|
+| 2D  | Two Dimensional               |
+| 3D  | Three Dimensional             |
+| AI  | Artificial Intelligence       |
+| AMR | Automated Mobile Robot        |
+| DM  | Data Matrix                   |
+| MVS | Machine Vision System         |
+| OCR | Optical Character Recognition |
+| QR  | Quick Response                |
+| ROI | Region of Interest            |
+| SKU | Stock Keeping Unit            |
+| SLW | Smart Logistics Warehouse     |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement needs not be present to claim conformance.
+
+# 6 Overview
+
+In smart logistics warehouse (SLW), based on the real-time management of the goods, shelves and logistics warehouse environments, artificial intelligence (AI) enabled visual analysis technology is widely used, which greatly improves the work efficiency of SLW. In the process of goods entering and leaving the SLW, the machine vision system (MVS) (e.g., high-resolution industrial cameras) collects and analyses label information of the goods in real-time, and quickly sorts goods according to the variety, material and weight of the goods. At the same time, it can identify abnormal appearance states such as stains, wrinkles and breakages, and can provide event reminders for abnormal goods, label errors and other issues. Through shelf status recognition, the real-time analysis of the shelf situation is carried out to determine whether the shelf is full and whether the goods are placed in a normal state, to realize the intelligent management of the shelf and improve the utilization rate of the shelf. The automated mobile robot (AMR) is responsible for the handling of goods in SLW. AMR's vision system collects ground conditions and surrounding environmental obstacles information, extracts feature information, matches database information, and completes map creation, positioning and navigation, which improves the efficiency of goods transportation. MVS identifies the stacking state of the goods and calculates the grasping pose, and controls such as the mechanical arm to perform the tasks of automatic grasping, palletizing and de-palletizing of the goods. The surveillance camera conducts real-time monitoring of the potential safety hazards in the SLW environment, the loading situation of the transport vehicle, and the use rate of the platform.
+
+# 7 Framework
+
+Figure 1 shows the framework of AI based MVS in SLW.
+
+![Figure 1 – Framework of artificial intelligence based machine vision system in a smart logistics warehouse. The diagram shows three layers: Application layer, Service layer, and Device layer. The Application layer includes goods sorting, palletizing/de-palletizing, handling, shelf inventory, and environment monitoring. The Service layer includes Open capability components (Algorithm and Basic services), Algorithm management components (scheduling, warehouse, training), Algorithm components (localization, measurement, processing, inspection, calibration, identification, alignment, navigation), and Basic components (access, configuration, control, operation and maintenance). The Device layer includes industrial camera, surveillance camera, code reader, AMR, mechanical arm, and others.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+|                                        |                                  |                          |                                  |                                            |
+|----------------------------------------|----------------------------------|--------------------------|----------------------------------|--------------------------------------------|
+| <b>Application layer</b>               |                                  |                          |                                  |                                            |
+| Goods sorting                          | Goods palletizing/de-palletizing | Goods handling           | Shelf inventory                  | Logistics warehouse environment monitoring |
+| <b>Service layer</b>                   |                                  |                          |                                  |                                            |
+| <b>Open capability components</b>      |                                  |                          |                                  |                                            |
+| Algorithm capability service           |                                  | Basic capability service |                                  |                                            |
+| <b>Algorithm management components</b> |                                  |                          | <b>Basic components</b>          |                                            |
+| Algorithm scheduling                   | Algorithm warehouse              | Algorithm training       | Device access                    |                                            |
+| <b>Algorithm components</b>            |                                  |                          | Device configuration             |                                            |
+| Target localization                    | Target measurement               | Image processing         | Device control                   |                                            |
+| Target calibration                     | Target identification            | Visual alignment         | Device operation and maintenance |                                            |
+| <b>Device layer</b>                    |                                  |                          |                                  |                                            |
+| Industrial camera                      | Surveillance camera              | Code reader              | AMR                              | Mechanical arm ...                         |
+
+Figure 1 – Framework of artificial intelligence based machine vision system in a smart logistics warehouse. The diagram shows three layers: Application layer, Service layer, and Device layer. The Application layer includes goods sorting, palletizing/de-palletizing, handling, shelf inventory, and environment monitoring. The Service layer includes Open capability components (Algorithm and Basic services), Algorithm management components (scheduling, warehouse, training), Algorithm components (localization, measurement, processing, inspection, calibration, identification, alignment, navigation), and Basic components (access, configuration, control, operation and maintenance). The Device layer includes industrial camera, surveillance camera, code reader, AMR, mechanical arm, and others.
+
+**Figure 1 – Framework of artificial intelligence based machine vision system in a smart logistics warehouse**
+
+The framework of AI based MVS in SLW (hereafter "MVS") consists of three layers: device layer, service layer and application layer.
+
+The device layer represents the devices used for data collection and control in MVS, including industrial cameras, surveillance cameras, code readers, AMRs and mechanical arms, etc.
+
+The service layer consists of four components, known as basic components, algorithm components, algorithm management components and open capability components. Basic components provide basic services for MVS, including device access, device configuration, device control, and device operation and maintenance. The algorithm component provides algorithm services for MVS, including algorithms for target localization, target measurement, image processing, appearance inspection, target calibration, target identification, visual alignment and visual navigation. The algorithm management component provides algorithm-related management services for MVS, including algorithm scheduling, algorithm warehouse management and algorithm training. The open capability component provides interface services for MVS, including algorithm capability services and basic capability services.
+
+The application layer includes service application scenarios such as goods sorting, goods palletizing/de-palletizing, goods handling, shelf inventory, and logistics warehouse environment monitoring.
+
+# 8 Requirements
+
+### 8.1 Device requirements
+
+- MVS is recommended to support data collection, including but not limited to video, image, point cloud, quick response (QR) code and barcode.
+- The industrial camera is recommended to support timed exposure and trigger delay functions.
+
+- The industrial camera is recommended to support region of interest (ROI) functions.
+- The industrial camera is recommended to support the centre horizontal resolution of output image no less than 85% of image height.
+- The code reader is recommended to support barcode format including Code 128, Code 39, etc.
+- The code reader is recommended to support QR code format including QR and data matrix (DM), etc.
+- The surveillance camera is recommended to support intelligent analysis function, including fire and smoke detection, AMR traffic jam detection, etc.
+- AMR is recommended to support QR code navigation and laser navigation.
+- AMR is recommended to support obstacle detection and path planning.
+
+### **8.2 Service requirements**
+
+#### **8.2.1 Requirements of basic components**
+
+- MVS is recommended to support device access, including device manual addition, device retrieve addition, and device deletion.
+- MVS is recommended to support device access protocols [ITU-T H.627].
+- MVS is recommended to support device configuration, including image parameters configuration (frame rate, exposure, gain and gamma), communication parameters configuration and image storage configuration (goods surface original image, goods surface original image cut-out and goods panorama image).
+- MVS is recommended to support device control, including data reading, command issuance, device timing, device restart and device reset.
+- MVS is recommended to support device operation and maintenance, including the management of device files information, device status, device upgrading and device alarm.
+
+#### **8.2.2 Requirements of algorithm components**
+
+- MVS is recommended to support target localization algorithms to locate or detect certain features in the image, including feature matching, grayscale matching, graphic localization, rectangle detection, vertex detection, etc.
+- MVS is recommended to support target calibration algorithms to realize the conversion from image coordinates to actual coordinates, including checkerboard calibration, N-point calibration, distortion calibration, mapping calibration, etc.
+- MVS is recommended to support target measurement algorithms to achieve distance measurement between target object elements in the image, including line-circle measurement, line-line measurement, circle-circle measurement, point-circle measurement, point-line measurement, distance detection, etc.
+- MVS is recommended to support target identification algorithms to realize the identification of target objects in the image, including barcode recognition, QR code recognition, optical character recognition (OCR), etc.
+- MVS is recommended to support image processing algorithms to realize image pre-processing of the target image, including image filtering, image enhancement, distortion correction, graph scaling and graph stitching, etc.
+
+NOTE – When the image has poor contrast, more burrs, more interference and less obvious features, image pre-processing can be considered.
+
+- MVS is recommended to support visual alignment algorithms to calculate the amount of movement (positional movement and angular movement) required from object alignment to the target object, including single-point alignment, point set alignment, line alignment, etc.
+- MVS is recommended to support appearance inspection algorithms to verify and compare target images with standard images to find appearance defects, including detection of printed characters and patterns appearance defects, surface defect detection without texture background, linear edge defect detection, arc edge defect detection, etc.
+- MVS is recommended to support visual navigation algorithms, and to complete the autonomous navigation and positioning of the target object by associating the image information collected by the camera with the actual position of the target object.
+
+#### **8.2.3 Requirements of algorithm management components**
+
+- MVS is recommended to support algorithm scheduling, realizes the scheduling and management of algorithm resources, including algorithm task configuration, algorithm task control (start, execution and cancellation), algorithm time-consuming statistics, and algorithm scheduling result storage.
+- MVS is recommended to support algorithm tasks of adding, deleting, starting and stopping.
+- MVS is recommended to support algorithm task configuration, including data source devices, data formats, algorithm types, algorithm parameters.
+- MVS is recommended to support computing resource management, assign computing resources to algorithm tasks for scheduling, and support viewing computing resource usage situation.
+- MVS is recommended to support algorithm warehouse management, including adding, deleting, modifying and querying.
+- MVS is recommended to support algorithm training, including sample management, model training, and algorithm deployment.
+- MVS is recommended to support sample management, including sample data adding, deleting, modifying and querying.
+- MVS is recommended to support sample data annotation, including annotation data adding, deleting, modifying, and querying.
+- MVS is recommended to support the training task management, including training task adding, deleting, starting, and stopping, and support querying the progress and results of training tasks.
+- MVS is recommended to support model validation and evaluation.
+- MVS is recommended to support algorithm deployment.
+
+#### **8.2.4 Requirements of open capability components**
+
+- MVS is recommended to support algorithm capability services, including algorithm scheduling open capability, algorithm warehouse open capability and algorithm training open capability.
+- MVS is recommended to support basic capability services, including device access open capability, device configuration open capability, device control open capability, and device operation and maintenance open capability.
+
+### **8.3 Application requirements**
+
+#### **8.3.1 Requirements of goods sorting**
+
+- MVS is recommended to support the identification of the appearance, size and quantity of goods during the sorting process, and is not recommended to be restricted by the placement direction. The identification speed of the number of parcels is recommended  $\geq 5\,000$  pieces/hour, and the resolution of goods image collection is recommended  $\geq 6$  million pixels.
+- MVS is recommended to support the measurement of the length, width, height of the goods during the sorting process. The volume measurement range is recommended to support  $150\text{ mm} \times 150\text{ mm} \times 30\text{ mm}$  to  $1\,200\text{ mm} \times 1\,000\text{ mm} \times 700\text{ mm}$  (regular goods), and the measurement and identification accuracy is recommended less than  $\pm 10\text{ mm}$ .
+- MVS is recommended to support simultaneous identification of multiple sides of goods in the process of parcel sorting, and it is recommended to support simultaneous identification of six sides of goods.
+- MVS is recommended to support the identification of barcodes, QR codes and other label information on the surface of the goods during the sorting process. The code reading rate is recommended  $\geq 99\%$ , and the identification speed of a single barcode or QR code is recommended  $\leq 100\text{ ms}$ .
+- MVS is recommended to support the single identification of multi-goods label information during the sorting process.
+- MVS is recommended to support abnormal code identification during the sorting process, including surface dirt, damage, scratches, etc.
+- MVS is recommended to support the identification of abnormal status information, including goods accumulation, blockage and overlapping during the sorting process, and identification accuracy rate is recommended  $\geq 99\%$ .
+- MVS is recommended to support the collection of a complete and clear image of goods during the sorting process, which can clearly identify codes and label information.
+
+#### **8.3.2 Requirements of goods palletizing and de-palletizing**
+
+- MVS is recommended to support automatic identification of multiple stock keeping units (SKUs).
+- MVS is recommended to support the identification of goods abnormal states, including appearance defects, etc.
+- MVS is recommended to support the identification of the stacking method and volume size of the goods.
+- MVS is recommended to support the calculation of accurate grab location, placement location and trajectory location through intelligent algorithms to control the mechanical arm to quickly grab and stack goods.
+
+#### **8.3.3 Requirements of shelf inventory**
+
+- MVS is recommended to support the identification of the number of goods on the shelf.
+- MVS is recommended to support the identification of abnormal information, including dirty and damaged surfaces of goods.
+- MVS is recommended to support the identification of falling goods on the shelf, and is recommended to support the identification of goods that are at risk of falling.
+- MVS is recommended to support the identification of vacant and occupied status of shelves.
+- MVS is recommended to support the identification of shelf storage space volume.
+
+#### **8.3.4 Requirements of goods handling**
+
+- MVS is recommended to support the identification of label information on the surface of the AMR transported goods, the identification accuracy is recommended  $\geq 99\%$ , and the identification speed is recommended  $\leq 500$  ms.
+- MVS is recommended to support the identification of obstacles and environmental information around the AMR.
+- MVS is recommended to support the identification of ground identification mark information.
+- MVS is recommended to support shelf label identification, and the identification accuracy is recommended  $\geq 99\%$ .
+- MVS is recommended to support the automatic planning of handling routes of AMR based on the logistics warehouse map, surrounding obstacles and environmental information.
+
+#### **8.3.5 Requirements of logistics warehouse environment monitoring**
+
+- MVS is recommended to support the identification of abnormal environmental information, including smoke, fire and water leakage, etc.
+- MVS is recommended to support the identification of violent sorting and handling behaviours of workers.
+- MVS is recommended to support the identification of AMR traffic jam.
+- MVS is recommended to support the identification of falling goods during AMR handling.
+- MVS is recommended to support the identification of the accumulation of goods in a specific area.
+- MVS is recommended to support the identification of loaded vehicle information, including colour, licence plate, vehicle brand, etc.
+- MVS is recommended to support the identification of vehicle loading rate, including empty, half and full, etc.
+- MVS is recommended to support the identification of platform usage, including occupied, unoccupied.
+
+## Appendix I
+
+## Use cases of artificial intelligence based machine vision system in a smart logistics warehouse
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Figure I.1 shows a service scenario of smart logistics warehouse.
+
+![A 3D perspective diagram of a smart logistics warehouse. The main area shows a large warehouse floor with high shelves filled with orange boxes. Several yellow AMRs (Automated Mobile Robots) are moving through the aisles. On the left, two white trucks are docked at a loading bay, with a yellow forklift and a platform nearby. A conveyor belt system on the right leads to a 'Goods sorting' area. An inset image in the top right shows a close-up of a robotic arm performing 'Goods palletizing and de-palletizing'. Labels with red leader lines point to various components: 'AMR', 'Shelf', 'Goods', 'Transportation vehicle and platform', 'Goods handling', 'Shelf inventory', and 'Goods sorting'. The code 'F.747.12(22)' is in the bottom right corner.](bd671b21db63e6fdb2196e9b18502aac_img.jpg)
+
+A 3D perspective diagram of a smart logistics warehouse. The main area shows a large warehouse floor with high shelves filled with orange boxes. Several yellow AMRs (Automated Mobile Robots) are moving through the aisles. On the left, two white trucks are docked at a loading bay, with a yellow forklift and a platform nearby. A conveyor belt system on the right leads to a 'Goods sorting' area. An inset image in the top right shows a close-up of a robotic arm performing 'Goods palletizing and de-palletizing'. Labels with red leader lines point to various components: 'AMR', 'Shelf', 'Goods', 'Transportation vehicle and platform', 'Goods handling', 'Shelf inventory', and 'Goods sorting'. The code 'F.747.12(22)' is in the bottom right corner.
+
+**Figure I.1 – Service scenario of smart logistics warehouse**
+
+### I.1 Goods sorting
+
+In the SLW, the sorting of goods is accomplished by industrial cameras that identify the label, size, and appearance of the goods. Fast identification of labels can collect and classify transportation information such as barcodes and QR codes on goods. Identifying the size of goods can provide a volume basis for subsequent shelf placement and vehicle loading. Identifying the appearance of the goods can determine whether there are abnormalities such as damage, dirt, and scratches on the surface of the goods. At the same time, the abnormal state of the sorting process of the goods on the conveyor belt can be identified, such as the accumulation, blockage and falling of goods.
+
+### I.2 Goods palletizing and de-palletizing
+
+In the SLW, MVS (e.g., three-dimensional (3D) cameras) obtain goods depth information and high-definition two-dimensional (2D) images, generate goods appearance point cloud data, complete goods image positioning and segmentation through visual algorithms, and control mechanical arms to grasp, palletize and de-palletize goods. At the same time, according to the preset accumulation type, MVS identifies and verifies the placement method, and identify the appearance defects of the goods.
+
+### I.3 Shelf inventory
+
+In the SLW, the inventory of goods is completed by industrial cameras that identify the vacancy and occupancy status of the shelf, can count the vacancy rate of the shelf, and provide data support for the goods to be placed on the shelf. MVS identifies the volume of the shelf storage space, which can match the size of the goods to place goods and improve the utilization rate of the shelf. MVS identifies the number of goods on the shelf and carry out an inventory of goods. MVS identifies the
+
+surface of the goods on the shelf, such as damage, dirt and other information, to facilitate the judgment of whether there is an abnormality inside the goods. MVS identifies the goods that fall from the shelf or that are at risk of falling to ensure the safety of goods and people.
+
+### **I.4 Goods handling**
+
+In the SLW, the handling of goods is completed by AMR. The MVS of the AMR identifies the label information on the surface of the goods and matches the position of the goods on the shelf or transportation vehicle. The AMR machine vision service identifies the surrounding environment and obstacle information, and plans transportation routes and logistics storage maps. AMR identifies ground material information and judges the arrival area.
+
+### **I.5 Logistics warehouse environment monitoring**
+
+In the SLW, MVS monitors the potential safety hazards of the logistics warehouse environment, including smoke, fire, or water leakage. The MVS monitors the AMR's handling activities, including AMR transportation traffic jams, AMR transportation goods falling, etc. The MVS monitors the accumulation of goods in a specific area, and at the same time monitors the violent sorting and handling behaviour of workers. The MVS collects information on goods transportation vehicles, including vehicle body colour, licence plate, vehicle brand, etc., and collects in-vehicle loading rates to identify empty, half, and full situations.
+
+## Bibliography
+
+- [b-ITU-T F.748.16] Recommendation ITU-T F.748.16 (2022), *Requirements for applications and services in smart manufacturing based on machine vision.*
+- [b-ISO/IEC 2382] ISO/IEC 2382 (2015), *Information technology – Vocabulary.*
+- [b-ISO/IEC 11557] ISO/IEC 11557 (1992), *Information technology – 3,81 mm wide magnetic tape cartridge for information interchange – Helical scan recording – DDS-DC format using 60 m and 90 m length tapes.*
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+# Recommendation**ITU-T F.747.13 (09/2023)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+# **Requirements and reference framework of cloud-edge collaboration in industrial machine vision systems**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font overlaid on the globe.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.747.13
+
+# Requirements and reference framework of cloud-edge collaboration in industrial machine vision systems
+
+## Summary
+
+Recommendation ITU-T F.747.13 specifies requirements and reference framework of cloud-edge collaboration in industrial machine vision systems and provides use cases. The cloud-edge collaboration is a process (or method) that coordinates cloud computing and edge computing, dynamically allocates required computing, algorithm models, data, or other resources and jointly completes the same tasks (or objectives) agreed in advance. In industrial machine vision systems, cloud-edge collaboration includes resource collaboration (computing, network and storage), service collaboration (data, intelligence and task) and application collaboration (capability and management).
+
+This Recommendation is intended to guide the design and development of industrial machine vision systems.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.747.13 | 2023-09-13 | 16          | 11.1002/1000/15620 |
+
+## Keywords
+
+Cloud-edge collaboration, industrial machine vision systems, reference framework, requirements, use cases.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                             | Page |
+|---------------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                               | 1    |
+| 2 References.....                                                                           | 1    |
+| 3 Definitions .....                                                                         | 1    |
+| 3.1 Terms defined elsewhere .....                                                           | 1    |
+| 3.2 Terms defined in this Recommendation.....                                               | 2    |
+| 4 Abbreviations and acronyms .....                                                          | 2    |
+| 5 Conventions .....                                                                         | 3    |
+| 6 Overview of cloud-edge collaboration in industrial machine vision systems .....           | 3    |
+| 7 Requirements of cloud-edge collaboration in industrial machine vision systems.....        | 6    |
+| 7.1 Requirements of resource collaboration .....                                            | 6    |
+| 7.2 Requirements of service collaboration .....                                             | 7    |
+| 7.3 Requirements of application collaboration.....                                          | 8    |
+| 8 Reference framework of cloud-edge collaboration in industrial machine vision systems..... | 9    |
+| 8.1 Requirements of the cloud layer.....                                                    | 9    |
+| 8.2 Requirements of the edge layer .....                                                    | 11   |
+| Appendix I – Use cases of cloud-edge collaboration in industrial machine vision systems ... | 13   |
+| I.1 Quality inspection.....                                                                 | 13   |
+| I.2 Logistics sorting .....                                                                 | 13   |
+| I.3 Industrial manufacturing robots .....                                                   | 14   |
+| Bibliography.....                                                                           | 15   |
+
+
+
+# Recommendation ITU-T F.747.13
+
+## Requirements and reference framework of cloud-edge collaboration in industrial machine vision systems
+
+# 1 Scope
+
+This Recommendation specifies the requirements and reference framework of cloud-edge collaboration in industrial machine vision systems.
+
+The scope of this Recommendation includes:
+
+- Overview;
+- Requirements; and
+- Reference framework.
+
+Use cases of cloud-edge collaboration in industrial machine vision systems are provided in Appendix I.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T F.743.22] Recommendation ITU-T F.743.22 (2022), *Requirements and architecture of an algorithm-training system for intelligent video surveillance*.
+
+[ITU-T F.747.12] Recommendation ITU-T F.747.12 (2022), *Requirements for artificial intelligence based machine vision system in smart logistics warehouse*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 algorithm training** [ITU-T F.743.22]: A technology that learns the experience or the environment represented by the input data and upgrades the algorithm.
+
+**3.1.2 cloud computing** [b-ITU-T Y.3500]: Paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand.
+
+NOTE – Examples of resources include servers, operating systems, networks, software, applications and storage equipment.
+
+**3.1.3 collaboration** [b-ISO 13374-2]: A relation between two objects in a collaboration diagram, indicating that messages can pass back and forth between the objects.
+
+**3.1.4 edge computing** [b-ITU-T Y.3073]: This refers to a strategy to deploy the processing capability at the network edge where end terminals are connected, and to perform the processing of data which is derived from and fed to the end terminals.
+
+**3.1.5 federated machine learning** [b-IEEE 3652.1]: Federated machine learning is a framework or system that enables multiple participants to collaboratively build and use machine learning models without disclosing the raw and private data owned by the participants while achieving good performance.
+
+**3.1.6 homomorphic encryption** [b-ISO/IEC 20009-4]: Symmetric or asymmetric encryption that allows third parties to perform operations on plaintext data while keeping them in encrypted form.
+
+**3.1.7 incremental learning** [b-ISO/IEC 2382]: Multistage adaptive learning in which knowledge learned at one stage is transformed in order to accommodate new knowledge provided at subsequent stages.
+
+**3.1.8 inference** [b-ISO/IEC 2382]: Reasoning by which conclusions are derived from known premises.
+
+**3.1.9 machine vision** [b-ITU-T F.748.16]: Signal processing to acquire, process and interpret an image or video to support visual analysis for applications, such as automatic inspection, process control and guidance.
+
+**3.1.10 orchestration** [b-ISO/IEC TR 30102]: Composition for which there is one particular element used by the composition that oversees and directs the other elements.
+
+NOTE – The element that directs an orchestration by definition is different than the orchestration (composition instance) itself.
+
+**3.1.11 optical character recognition (OCR)** [b-ISO/IEC 22989]: Conversion of images of typed, printed, or handwritten text into machine-encoded text.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 cloud-edge collaboration:** A process (or method) that coordinates cloud computing and edge computing, dynamically allocates required computing, algorithm models, data, or other resources, and jointly completes the same tasks (or objectives) agreed in advance.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                |
+|------|--------------------------------|
+| 3D   | Three-Dimension                |
+| AGV  | Automated Guided Vehicle       |
+| AI   | Artificial Intelligence        |
+| AMR  | Automated Mobile Robot         |
+| CPU  | Central Processing Unit        |
+| ERP  | Enterprise Resource Planning   |
+| FPGA | Field Programmable Gate Array  |
+| GPU  | Graphics Processing Unit       |
+| MES  | Manufacturing Execution System |
+| NPU  | Neural-network Processing Unit |
+| OCR  | Optical Character Recognition  |
+| OCV  | Optical Character Verification |
+
+|      |                              |
+|------|------------------------------|
+| ONNX | Open Neural Network Exchange |
+| QMS  | Quality Management System    |
+| WMS  | Warehouse Management System  |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+- The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement needs not be present to claim conformance.
+- The keywords "**can optionally**" indicate an optional requirement which is permissible, without implying any sense of being recommended. These terms are not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+# 6 Overview of cloud-edge collaboration in industrial machine vision systems
+
+With the continuous improvement of industrial automation and intelligence requirements, industrial machine vision technology is widely used in intelligent manufacturing, smart logistics warehousing, smart energy and other scenarios. The data-intensive applications and computing intensive applications are continuously increasing, and the powerful computing and network resources of cloud computing collaborative with the high-speed response capability of edge computing can greatly improve the application level of machine vision systems in the industrial field.
+
+Cloud-edge collaboration is a process (or method) that coordinates cloud computing and edge computing, dynamically allocates required computing, algorithm models, data, or other resources, and jointly completes the same tasks (or objectives) agreed in advance.
+
+Cloud computing can achieve global, non-real-time, long-term big data processing and analysis, and can play an important role in the fields of long-term maintenance, service decision support, etc. Edge computing can achieve local, real-time and short-term data processing and analysis, and can better support real-time intelligent decision-making and execution of local services.
+
+The application of cloud-edge collaboration in industrial machine vision systems can optimize the allocation and utilization of resources, achieve effective collaboration of data and computing processes, and strengthen the perception capability of industrial machine vision systems. Real-time data processing can relieve bandwidth pressure, and complete the data perception, analysis, decision-making and evaluation in the whole cycle.
+
+In this Recommendation, the cloud is equivalent to cloud computing, and the edge is equivalent to edge computing.
+
+Typical scenarios of cloud-edge collaboration in industrial machine vision systems (see Appendix I for use cases) include:
+
+## Scenario A: High real-time performance requirements
+
+In the industrial production environment, certain processes require high real-time performance. For example, the defect detection processes use the industrial camera to collect the image of the product surface, analyses whether the product has defects in real-time, and classifies the defective products through the mechanical arm. This requires real-time inference on the edge which closes to the
+
+pipeline. The cloud completes the algorithm training and deploys the algorithm models to the edge. Through cloud-edge collaboration algorithm models achieve efficient and fast iterations that continuously improve the accuracy of defect identification.
+
+## Scenario B: High data security requirements
+
+For enterprises and factories with high requirements for data security, the raw data collected by industrial devices cannot be uploaded to the cloud. The edge deployed in the trusted domain uses technologies such as federated machine learning and homomorphic encryption to upload the processed data (such as intermediate computing results and desensitization data) to the cloud to complete the training, analysis and applications.
+
+Figure 1 shows the conceptual diagram of a cloud-edge collaboration.
+
+![Conceptual diagram of a cloud-edge collaboration showing three levels of collaboration: Application, Service, and Resource between Edge and Cloud layers.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg)
+
+The diagram illustrates the conceptual architecture of cloud-edge collaboration. It consists of two main vertical columns: **Edge** on the left and **Cloud** on the right. Each column is divided into three horizontal layers, each containing specific functional blocks.
+
+- Edge Column:**
+  - Top Layer:** Management, Capability
+  - Middle Layer:** Task, Intelligence, Data
+  - Bottom Layer:** Computing, Network, Storage
+- Cloud Column:**
+  - Top Layer:** Management, Capability
+  - Middle Layer:** Task, Intelligence, Data
+  - Bottom Layer:** Computing, Network, Storage
+
+Three horizontal double-headed arrows connect the corresponding layers between Edge and Cloud, representing different types of collaboration:
+
+- Application collaboration:** Connects the top layers (Management and Capability) of both Edge and Cloud.
+- Service collaboration:** Connects the middle layers (Task, Intelligence, and Data) of both Edge and Cloud.
+- Resource collaboration:** Connects the bottom layers (Computing, Network, and Storage) of both Edge and Cloud.
+
+F.747.13(23)
+
+Conceptual diagram of a cloud-edge collaboration showing three levels of collaboration: Application, Service, and Resource between Edge and Cloud layers.
+
+**Figure 1 – Conceptual diagram of a cloud-edge collaboration**
+
+Cloud-edge collaboration mainly includes resource collaboration, service collaboration and application collaboration.
+
+Resource collaboration is the collaboration of computing, network and storage resources between the cloud and edge. Through the unified management of resources, resource collaboration enriches the types of resource entities, expands the area of resource management, and improves the decision-making capability of resource scheduling. The orchestration and scheduling of resources extend from the resource-rich cloud to the resource-constrained edge, providing an overall view of the resources, so that edge-to-cloud and edge-to-edge resources can be scheduled and collaborated on demand, to optimize the resource utilization from a global perspective.
+
+Service collaboration is the collaboration of tasks, intelligence and data between the cloud and the edge. Based on the resource collaboration and scheduling capabilities between cloud and edge, the service collaboration establishes a multi-layer collaboration of cloud and edge, decomposes large-scale and complex services into tasks, and reasonably plans the storage and transmission of data between cloud and edge. Combined with technologies such as federated machine learning and incremental learning, the orchestrated tasks are allocated to the cloud and edge for joint training and joint inference on-demand, which can realize the mutual extension and collaborative operation of intelligence services between cloud and edge and improve the efficiency and performance.
+
+Application collaboration is the collaboration of management and capability between cloud and edge. Based on the resource and service collaboration between cloud and edge, the application
+
+collaboration realizes the unified registration and access of edge applications, consistently distributes the deployment and centralized full-lifecycle management, including push, installation, update, and the uninstall of applications. Based on the capability hierarchy of cloud and edge, the allocation strategies are designed according to the priority and dependencies of service attributes, while completing the high availability guarantee and live migration of applications to meet the requirements of users.
+
+Figure 2 shows the information interaction model between the cloud and the edge.
+
+![Figure 2 – Information interaction model between cloud and edge. The diagram illustrates the flow of data, results, and algorithm models between Cloud and Edge components. Cloud components include Applications, Algorithm training, Algorithm warehouse, and Algorithm inference. Edge components include Applications, Algorithm warehouse, Algorithm inference, and Data acquisition. Arrows indicate the direction of interaction, labeled (a) through (m).](e9314c83043183351ed74908e9bf2f90_img.jpg)
+
+The diagram shows the information interaction model between cloud and edge. It is divided into two main sections: Cloud and Edge.
+
+- Cloud Section:**
+  - Applications:** A large grey box at the top.
+  - Algorithm training:** A grey box below Applications.
+  - Algorithm warehouse:** A grey box to the right of Algorithm training.
+  - Algorithm inference:** A grey box to the right of Algorithm warehouse.
+- Edge Section:**
+  - Applications:** A grey box on the right side.
+  - Algorithm warehouse:** A grey box on the left side, above Algorithm inference.
+  - Algorithm inference:** A grey box in the middle, below Algorithm warehouse.
+  - Data acquisition:** A grey box at the bottom right.
+  - Algorithm training:** A grey box at the bottom left.
+
+**Interactions (Arrows):**
+
+- (a) Data acquisition → Algorithm inference
+- (b) Data acquisition → Algorithm training
+- (c) Algorithm training → Algorithm warehouse
+- (d) Algorithm inference → Applications
+- (e) Algorithm inference → Applications
+- (f) Algorithm inference → Applications
+- (g) Algorithm inference → Applications
+- (h) Algorithm training → Algorithm warehouse
+- (i) Algorithm warehouse → Algorithm inference
+- (j) Algorithm warehouse → Algorithm warehouse
+- (k) Algorithm warehouse → Algorithm inference
+- (l) Algorithm inference → Algorithm training
+- (m) Algorithm training → Algorithm inference
+
+**Legend:**
+
+- Data (black arrow)
+- Result (red arrow)
+- Algorithm model (blue arrow)
+
+F.747.13(23)
+
+Figure 2 – Information interaction model between cloud and edge. The diagram illustrates the flow of data, results, and algorithm models between Cloud and Edge components. Cloud components include Applications, Algorithm training, Algorithm warehouse, and Algorithm inference. Edge components include Applications, Algorithm warehouse, Algorithm inference, and Data acquisition. Arrows indicate the direction of interaction, labeled (a) through (m).
+
+**Figure 2 – Information interaction model between cloud and edge**
+
+The information interaction between cloud and edge mainly includes the data, results and the algorithm models. In the information interaction model, edge includes data collection/acquisition, algorithm inference, algorithm training, algorithm warehouse, edge application, etc.; cloud includes algorithm training, algorithm warehouse, algorithm inference, cloud application, etc.
+
+Typical information interaction process is as follows:
+
+### **a. Cloud training and edge inference**
+
+- The edge uploads the collected data to the algorithm training unit on cloud for algorithm training unit through (c);
+- The algorithm training unit on cloud performs algorithm training and sends the trained algorithm models to the algorithm warehouse unit on cloud through (h);
+- The algorithm warehouse unit on cloud sends the algorithm models to the algorithm warehouse unit on edge based on requirements through (j);
+- The algorithm warehouse unit on edge deploys the algorithm models to the algorithm inference unit on edge through (k) and starts the inference tasks;
+- The data acquisition unit on edge sends the original data to the algorithm inference unit on edge for inference through (a);
+
+- The algorithm inference unit on edge sends the inference results to the edge application through (e) or uploads the inference results to the cloud application through (g).
+- b. Cloud and edge joint training based on federated machine learning**
+- The edge sends the collected data to the algorithm training unit on edge through (b);
+  - The algorithm training unit on edge performs algorithm training and uploads the intermediate results generated during the training process to the algorithm training unit on cloud through (m);
+  - The algorithm training unit on cloud uses the federated learning framework to aggregate the intermediate results generated by multiple edge to a global algorithm model, and then sends the global algorithm model to the algorithm warehouse unit on cloud through (h).
+- c. Cloud and edge joint training based on incremental learning**
+- The edge uploads the collected data to the algorithm training unit on cloud for algorithm training unit through (c);
+  - The algorithm training unit on cloud performs algorithm training and sends the trained algorithm models to the algorithm warehouse unit on cloud through (h);
+  - The algorithm warehouse unit on cloud sends the algorithm models to the algorithm warehouse unit on edge based on requirements through (j);
+  - The algorithm warehouse unit on edge sends the algorithm models to the algorithm training unit on edge through (i);
+  - The edge sends the collected data to the algorithm training unit on edge through (b);
+  - The algorithm training unit on edge sends the incremental learning algorithm models to the algorithm warehouse unit on edge through (i).
+- d. Cloud and edge joint inference**
+- The algorithm warehouse unit on edge deploys the algorithm models to the algorithm inference unit on edge through (k) and starts the inference tasks;
+  - The data acquisition unit on edge sends the original data to the algorithm inference unit on edge for inference through (a);
+  - The algorithm inference unit on edge uploads the inference results to the cloud application through (g).
+  - The algorithm warehouse unit on the cloud deploys the algorithm models to the algorithm inference unit on the cloud through (i) and starts the inference tasks;
+  - The data acquisition unit on edge uploads the original data to the algorithm inference unit on the cloud for inference through (d);
+  - The algorithm inference unit on the cloud sends the inference results to the cloud application through (f);
+  - The edge and cloud side inference results are aggregated into cloud applications to achieve specific service requirements.
+
+# **7 Requirements of cloud-edge collaboration in industrial machine vision systems**
+
+In this Recommendation, requirements specific to the cloud-edge collaboration in industrial machine vision systems (hereafter "the system") are identified.
+
+## **7.1 Requirements of resource collaboration**
+
+- RRC1: The system is recommended to support the application, reservation and release of resources (computing, storage and network);
+
+- RRC2: The system is recommended to support resources self-discovery, self-maintenance and self-management;
+- RRC3: The system is recommended to support resources reuse mechanisms, including reuse by time and reuse by domain;
+- RRC4: The system is recommended to support resource scheduling between cloud and edge on-demand;
+- RRC5: The system is recommended to support the computing capability model generation, computing resource normalization of heterogeneous computing devices, and provide attribute and status information for scheduling;
+- RRC6: The system is recommended to support resource information modelling and overall view generation of resources scheduling between cloud and edge;
+- RRC7: The system is recommended to support the heterogeneous computing resources virtualization and pooling, computing resources including central processing unit (CPU), graphics processing unit (GPU), neural-network processing unit (NPU) and field programmable gate array (FPGA);
+- RRC8: The system is recommended to support the resource status synchronization between cloud and edge, including the idle and occupied status of computing resources, storage resources and bandwidth resources;
+- RRC9: The system is recommended to support resource fault isolation, performance isolation and security isolation.
+
+## **7.2 Requirements of service collaboration**
+
+### **7.2.1 Requirements of data collaboration**
+
+- RDC1: The system is recommended to support data aggregation, storage, retrieval, invocation and association;
+- RDC2: The system is recommended to support data synchronization between cloud and edge, including structured data, unstructured data and semi-structured data;
+- RDC3: The system is recommended to support unified processing and the conversion of different data formats;
+- RDC4: The system is recommended to support data conversion under different spatiotemporal coordinate systems;
+- RDC5: The system is recommended to support sample data aggregation between cloud and edge;
+- RDC6: The system is recommended to support sample data de-duplication between cloud and edge;
+
+NOTE – The sample data is used for training.
+
+- RDC7: The system is recommended to support redundant, multiple copies, or erasure code data storage;
+- RDC8: The system is recommended to support data compression and encrypted transmission.
+
+### **7.2.2 Requirements of intelligence collaboration**
+
+- RIC1: The system is recommended to support operating machine learning frameworks on cloud and edge, such as TensorFlow and PyTorch;
+- RIC2: The system is recommended to support the algorithm models updating and maintenance on cloud and edge;
+
+- RIC3: The system is recommended to support cloud training with edge inference mode;
+- RIC4: The system is recommended to support the cloud and edge joint inference mode;
+- RIC5: The system is recommended to support unified metadata description of inference results between cloud and edge;
+- RIC6: The system is recommended to support the cloud and edge joint training mode based on federated machine learning;
+- RIC7: The system is recommended to support cloud and edge joint training mode based on incremental learning;
+- RIC8: The system is recommended to support algorithm model lightweight to adapt the computing capabilities on cloud and edge;
+- RIC9: The system is recommended to support the general representation of algorithm models, so that the trained algorithm models can be deployed and operated without conversion between cloud and edge.
+
+### **7.2.3 Requirements of task collaboration**
+
+- RTC1: The system is recommended to support unified tasks scheduling and tasks distribution for execution between cloud and edge;
+- RTC2: The system is recommended to support the tasks migration to the cloud or edge for execution when edge devices have insufficient computing resources or when abnormal conditions occur;
+- RTC3: The system is recommended to support priority definition and resource pre-emption of tasks;
+- RTC4: The system is recommended to support the generation of task scheduling strategies based on task timing, network bandwidth, computing resources and data proximity;
+- RTC5: The system is recommended to support dynamic adjustment, flexible configuration and combined use of task scheduling strategies;
+- RTC6: The system is recommended to support the execution isolation of task instances, to ensure user data security and hardware device safety.
+
+## **7.3 Requirements of application collaboration**
+
+### **7.3.1 Requirements of capability collaboration**
+
+- RCC1: The system is recommended to support unified metadata description of capabilities on cloud and edge;
+- RCC2: The system is recommended to support capabilities convergence and synchronization between cloud and edge;
+- RCC3: The system is recommended to support capabilities, including analysis, enhancement, and retrieval of video and image data;
+- RCC4: The system is recommended to support capabilities, including acquisition, transmission, storage, display and control of multimedia data;
+- RCC5: The system is recommended to support overall view generation of capabilities on cloud and edge.
+
+### **7.3.2 Requirements of management collaboration**
+
+- RMC1: The system is recommended to support the splitting of services into multiple collaborative task execution units for scheduling and operation;
+- RMC1: The system is recommended to support planning collaboration strategies based on service attributes (priorities, dependencies) and cloud and edge capabilities.
+
+# 8 Reference framework of cloud-edge collaboration in industrial machine vision systems
+
+Figure 3 shows the reference framework of cloud-edge collaboration in industrial machine vision systems.
+
+![Figure 3: Reference framework of cloud-edge collaboration in industrial machine vision systems. The diagram shows a hierarchical structure. On the left, a large box labeled 'Industrial machine vision systems' contains three layers: 'Cloud layer', 'Edge layer', and 'Production management systems'. The 'Cloud layer' is divided into 'Application components' (Detection, Identification, Localization, Measurement, ...), 'Intelligent components' (Algorithm scheduling, Algorithm inference, Algorithm training, Algorithm warehouse), and 'Fundamental components' (Visual data management, Task orchestration, Collaboration management, Capability management, Device management, Resource management). The 'Edge layer' is divided into 'Algorithm warehouse', 'Visual data processing', 'Task execution', 'Algorithm inference', 'Visual data acquisition', 'Visual data storage', 'Algorithm training', 'Device management', and 'Resource management'. The 'Production management systems' are shown on the right, connected to the 'Industrial machine vision systems' box, and include MES, WMS, QMS, ERP, and ... (ellipsis).](724c7777b608e53be38b12b6fb3c43bc_img.jpg)
+
+**Industrial machine vision systems**
+
+**Cloud layer**
+
+**Application components**
+
+Detection    Identification    Localization    Measurement    ...
+
+**Intelligent components**
+
+Algorithm scheduling    Algorithm inference  
+Algorithm training    Algorithm warehouse
+
+**Fundamental components**
+
+Visual data management    Task orchestration  
+Collaboration management    Capability management  
+Device management    Resource management
+
+**Edge layer**
+
+Algorithm warehouse    Visual data processing    Task execution  
+Algorithm inference    Visual data acquisition    Visual data storage  
+Algorithm training    Device management    Resource management
+
+**Production management systems**
+
+MES  
+WMS  
+QMS  
+ERP  
+...
+
+F.747.13(23)
+
+Figure 3: Reference framework of cloud-edge collaboration in industrial machine vision systems. The diagram shows a hierarchical structure. On the left, a large box labeled 'Industrial machine vision systems' contains three layers: 'Cloud layer', 'Edge layer', and 'Production management systems'. The 'Cloud layer' is divided into 'Application components' (Detection, Identification, Localization, Measurement, ...), 'Intelligent components' (Algorithm scheduling, Algorithm inference, Algorithm training, Algorithm warehouse), and 'Fundamental components' (Visual data management, Task orchestration, Collaboration management, Capability management, Device management, Resource management). The 'Edge layer' is divided into 'Algorithm warehouse', 'Visual data processing', 'Task execution', 'Algorithm inference', 'Visual data acquisition', 'Visual data storage', 'Algorithm training', 'Device management', and 'Resource management'. The 'Production management systems' are shown on the right, connected to the 'Industrial machine vision systems' box, and include MES, WMS, QMS, ERP, and ... (ellipsis).
+
+**Figure 3 – Reference framework of cloud-edge collaboration in industrial machine vision systems**
+
+The reference framework of cloud-edge collaboration in industrial machine vision systems consists of the cloud layer and edge layer. At the same time, industrial machine vision systems can interact with external production management systems, such as manufacturing execution systems (MES), warehouse management systems (WMS), quality management systems (QMS), enterprise resource planning (ERP), etc.
+
+The cloud layer includes application components, intelligent components and fundamental components. Applications include detection, identification, localization, measurement, etc. Intelligent components include algorithm training, algorithm warehouse, algorithm scheduling and algorithm inference. The fundamental components include visual data management, task orchestration, collaboration management, capability management, device management and resource management.
+
+The edge layer includes algorithm warehouse, algorithm inference, algorithm training, resource management, device management, visual data collection/acquisition, visual data storage, visual data processing and task execution.
+
+The requirements for cloud and edge layers are as follows:
+
+## 8.1 Requirements of the cloud layer
+
+### 8.1.1 Requirements of application components
+
+The requirements of application components on the cloud include:
+
+- RA1: It is recommended to support machine vision applications for industrial fields, such as detection, identification, localization, measurement, etc.;
+
+- RA2: It is recommended to support application management, including push, installation, update and uninstall;
+- RA3: It is recommended to support application disassembly as a service, deploying to the edge in the form of containers;
+- RA4: It is recommended to support multi-tenant application isolation.
+
+### 8.1.2 Requirements of intelligent components
+
+The requirements of intelligent components on the cloud include:
+
+- RICO1: It is recommended to support sample data management and algorithm training [ITU-T F.743.22];
+- RICO2: It is recommended to support multiple algorithm model management in the cloud algorithm warehouse, including addition, deletion and deployment;
+- RICO3: It is recommended to support the management of the edge algorithm warehouse, including querying, deploying and uploading;
+- RICO4: It is recommended to support algorithm inference tasks operation, including start, pause and stop;
+- RICO5: It is recommended to support unified scheduling of algorithm tasks between cloud and edge;
+- RICO6: It is recommended to support the algorithm model in a general format such as open neural network exchange (ONNX) [b-Onnx] format;
+- RICO7: It is recommended to support algorithm model clipping, compression and optimization.
+
+### 8.1.3 Requirements of fundamental components
+
+The requirements of fundamental components on the cloud include:
+
+- RFC1: It is recommended to support the management of the edge including access, control, operation and maintenance;
+- RFC2: It is recommended to support physical resource information aggregation and usage monitoring on cloud and edge;
+- RFC3: It is recommended to support data management by cloud storage;
+- RFC4: It is recommended to support unified management of visual data, including storage, backup and migration;
+- RFC5: It is recommended to support the management of collaboration strategies, including adding, deleting, modifying and querying;
+- RFC6: It is recommended to support the management of task scheduling strategies, including adding, deleting, modifying and checking;
+- RFC7: It is recommended to support the execution of task scheduling strategies, including creating, starting, stopping and deleting tasks on cloud and edge;
+- RFC8: It is recommended to support task operation status querying and resource consumption monitoring;
+- RFC9: It is recommended to support cloud and edge capability aggregation and management, and provide an overall view of the entire domains;
+- RFC10: It is recommended to support computing resource virtualization on the cloud, including CPU, GPU, or other artificial intelligence (AI) accelerating processors;
+- RFC11: It is recommended to support a unified container orchestration framework on cloud and edge, and applications with unified distribution and unified governance.
+
+## **8.2 Requirements of the edge layer**
+
+### **8.2.1 General requirements**
+
+The general requirements on edge include:
+
+- RGR1: It is recommended to support registering to the cloud, reporting edge capabilities to the cloud, and management by cloud;
+- RGR2: It is recommended to support signalling interaction and data sharing with multiple edge devices;
+- RGR3: It is recommended to support offline operation strategies, including autonomous operation and task migration.
+
+### **8.2.2 Requirements of resource management**
+
+The requirements of resource management on edge include:
+
+- RRM1: It is recommended to support edge resource information and usage monitoring;
+- RRM2: It is recommended to support reporting resource information and usage status to the cloud.
+
+### **8.2.3 Requirements of device management**
+
+The requirements of device management on edge include:
+
+- RDM1: It is recommended to support multiple types of edge devices access such as industrial cameras, automated guided vehicles (AGV), automated mobile robots (AMR), mechanical arms, surveillance cameras, code readers, three-dimension (3D) cameras, laser radars, etc.;
+- RDM2: It is recommended to support edge devices configuration, including codec configuration, network configuration and storage configuration;
+- RDM3: It is recommended to support edge devices control, including restarting, upgrading, suspending operation and resuming operations;
+- RDM4: It is recommended to support edge devices event subscription and notification;
+- RDM5: It is recommended to support edge devices operation and maintenance, including status information collection, status abnormality alarm;
+- RDM6: It is recommended to support edge devices detection, including network link detection, video and image quality diagnosis;
+- RDM7: It is recommended to satisfy the device requirements defined in [ITU-T F.747.12].
+
+### **8.2.4 Requirements of algorithm warehouse**
+
+The requirements of algorithm warehouse on edge include:
+
+- RAW1: It is recommended to support multiple algorithm model management, including addition, deletion and deployment;
+- RAW2: It is recommended to support algorithm model deployment to edge devices on-demand.
+
+### **8.2.5 Requirements of algorithm inference**
+
+The requirements of algorithm inference on edge include:
+
+- RAI1: It is recommended to support algorithm inference and cache the inference results locally for task use;
+- RAI2: It is recommended to support reporting inference results to cloud applications;
+
+- RAI3: It is recommended to support common machine vision algorithm models including but not limited to target localization, target measurement, target identification, etc.;
+- RAI4: It is recommended to support the decomposition and allocation of algorithm inference tasks to multiple edge devices.
+
+NOTE – Edge devices jointly complete partial inference tasks to reduce inference pressure.
+
+### **8.2.6 Requirements of algorithm training**
+
+The requirements of algorithm training on edge include:
+
+- RAT1: It is recommended to support algorithm training and storage of the trained algorithm model into the algorithm warehouse;
+- RAT2: It is recommended to support federated machine learning with multi-edge;
+- RAT3: It is recommended to support incremental learning.
+
+### **8.2.7 Requirements of visual data collection**
+
+The requirements of visual data collection on edge include:
+
+- RVDC1: It is recommended to support multiple types of industrial data collection, including video, images and point clouds;
+- RVDC2: It is recommended to support multiple resolutions, including 1 million, 3 million, 5 million, 10 million and 12 million pixels;
+- RVDC3: It is recommended to support multiple pixel depths, including 8 bits, 10 bits, 12 bits and 14 bits;
+- RVDC4: It is recommended to support multiple frame rates, including 5, 10, 50, 100 and 200 frames per second (fps).
+
+### **8.2.8 Requirements of visual data storage**
+
+The requirement of visual data storage on edge includes:
+
+- RVDS1: It is recommended to support expandable storage capacity;
+- RVDS2: It is recommended to support data redundancy protection and backup;
+- RVDS3: It is recommended to support universal data storage formats, such as block storage, file storage and object storage.
+
+### **8.2.9 Requirements of visual data processing**
+
+The requirements of visual data processing on edge include:
+
+- RVDP1: It is recommended to support data pre-processing, including image zooming, image filling, image rotation and image enhancement;
+- RVDP2: It is recommended to support data analysis, including data filtering, data classification and data retrieval;
+- RVDP3: It is recommended to support multi-modal data fusion of multiple edge devices.
+
+#### **8.2.10 Requirements of task execution**
+
+The requirements of task execution on edge include:
+
+- RTE1: It is recommended to support the execution of tasks, such as target localization, target measurement and target identification;
+- RTE2: It is recommended to support reporting task execution status to the cloud;
+- RTE3: It is recommended to support task execution in the form of containers on edge devices;
+- RTE4: It is recommended to support multi-tenant task isolation.
+
+## Appendix I
+
+### Use cases of cloud-edge collaboration in industrial machine vision systems
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Figure I.1 shows the service scenario of cloud-edge collaboration in industrial machine vision systems.
+
+![Diagram illustrating the service scenario of cloud-edge collaboration in industrial machine vision systems. The diagram shows an Industrial environment (represented by a factory floor with conveyor belts) connected to an Industrial machine vision system (containing Cloud and Edge components), which in turn connects to a Production management system. Data flows from the Industrial environment to the Edge, then to the Cloud, and finally to the Production management system. Results flow from the Cloud to the Production management system. Algorithm models flow from the Cloud to the Edge. Control signals flow from the Production management system to the Edge, and from the Edge to the Industrial environment.](10781f43062bf3e9601a1e086710556c_img.jpg)
+
+The diagram illustrates the service scenario of cloud-edge collaboration in industrial machine vision systems. It is divided into three main components: **Industrial environment** (left), **Industrial machine vision system** (center), and **Production management system** (right). The **Industrial machine vision system** contains two sub-components: **Cloud** and **Edge**. The **Industrial environment** sends **Data** (black arrow) to the **Edge**. The **Edge** sends **Result** (red arrow) to the **Cloud**. The **Cloud** sends **Algorithm model** (blue arrow) to the **Edge**. The **Cloud** sends **Result** (red arrow) to the **Production management system**. The **Edge** sends **Control** (green arrow) to the **Industrial environment**. The **Production management system** sends **Control** (green arrow) to the **Edge**. A legend at the bottom indicates: **Data** (black arrow), **Result** (red arrow), **Algorithm model** (blue arrow), and **Control** (green arrow). The diagram is labeled F.747.13(23).
+
+Diagram illustrating the service scenario of cloud-edge collaboration in industrial machine vision systems. The diagram shows an Industrial environment (represented by a factory floor with conveyor belts) connected to an Industrial machine vision system (containing Cloud and Edge components), which in turn connects to a Production management system. Data flows from the Industrial environment to the Edge, then to the Cloud, and finally to the Production management system. Results flow from the Cloud to the Production management system. Algorithm models flow from the Cloud to the Edge. Control signals flow from the Production management system to the Edge, and from the Edge to the Industrial environment.
+
+**Figure I.1 – Service scenario of cloud-edge collaboration in industrial machine vision systems**
+
+The data collected by devices in an industrial production environment can be analysed and processed in real-time at the edge, and the results can be sent to the production management system for decision-making and control. At the same time, the processed data can be uploaded to the cloud to complete the algorithm training, and the cloud deploys the algorithm model to the edge and the industrial devices. The cloud can conduct big data analysis based on data, and the production management system can conduct decision-making and control devices in the industrial production environment based on the results produced by the cloud.
+
+### I.1 Quality inspection
+
+In automated assembly lines, a certain number of defective products are produced in various stages of continuous mass production. To improve the yield rate of manufacturing enterprises, industrial machine vision technology plays a significant role in defective product elimination, quality control and cost control. Industrial cameras and X-ray machines can be used to collect internal and external defects of the products. The collected information on the edge can be identified and analysed at a high speed to determine the defective products. The defect recognition algorithm models are continuously trained and upgraded on the cloud which improves the recognition accuracy. It can be applied to the pharmaceutical industry, electronic component processing industry, precision equipment quality inspection industry, etc.
+
+### I.2 Logistics sorting
+
+[ITU-T F.747.12] defines the general requirements and framework for intelligent logistics warehousing machine vision systems. In the logistics and warehousing industry, massive package information needs to be classified and processed according to the destination or type. This requires industrial cameras' high-speed acquisition of text, barcode, and other information on package surface labels, real-time identification and analysis of label images at the edges, and cloud-completed algorithm training to improve identification accuracy, thereby completing optical character recognition (OCR) and optical character verification (OCV).
+
+## **I.3 Industrial manufacturing robots**
+
+In industrial manufacturing scenarios, the industrial machine vision system can locate the position and direction of the target, compare the target with the specified tolerance, determine the target position, and verify whether the grasping and placement actions are correct. In scenarios such as mechanical arm grabbing and goods handling, real-time path planning at the edge can achieve accurate grabbing and transportation. Big data analysis of data is performed in the cloud, and a grabbing path model and transportation global map are constructed. At the same time, industrial machine vision technology can replace laser, magnetic conductivity and other technologies, greatly reducing costs.
+
+## Bibliography
+
+- [b-ITU-T F.748.16] Recommendation ITU-T F.748.16 (2022), *Requirements for applications and services in smart manufacturing based on machine vision.*
+- [b-ITU-T Y.3073] Recommendation ITU-T Y.3073 (2019), *Framework for service function chaining in information-centric networking.*
+- [b-ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014), *Information technology – Cloud computing – Overview and vocabulary.*
+- [b-IEEE 3652.1] IEEE 3652.1-2020, *IEEE Guide for Architectural Framework and Application of Federated Machine Learning.*  
+<<https://ieeexplore.ieee.org/document/9382202>>
+- [b-ISO 13374-2] ISO 13374-2:2007, *Condition monitoring and diagnostics of machines – Data processing, communication and presentation – Part 2: Data processing.*  
+<<https://www.iso.org/standard/36645.html>>
+- [b-ISO/IEC 20009-4] ISO/IEC 20009-4:2017, *Information technology – Security techniques – Anonymous entity authentication – Part 4: Mechanisms based on weak secrets.*  
+<<https://www.sis.se/produkter/informationsteknik-kontorsutrustning/itsakerhet/isoiec-20009-42017/>>
+- [b-ISO/IEC 22989] ISO/IEC 22989:2022, *Information technology – Artificial intelligence – Artificial intelligence concepts and terminology.*  
+<<https://www.iso.org/standard/74296.html>>
+- [b-ISO/IEC 2382] ISO/IEC 2382:2015, *Information technology – Vocabulary.*  
+<<https://www.iso.org/standard/63598.html>>
+- [b-ISO/IEC TR 30102] ISO/IEC TR 30102:2012, *Information technology – Distributed Application Platforms and Services (DAPS) – General technical principles of Service Oriented Architecture.*  
+<[https://www.iso.org/standard/53222.html#:~:text=ISO%2FIEC%20TR%2030102%3A2012%20describes%20the%20general%20technical%20principles\\_of%20terms%20relevant%20to%20SOA.](https://www.iso.org/standard/53222.html#:~:text=ISO%2FIEC%20TR%2030102%3A2012%20describes%20the%20general%20technical%20principles_of%20terms%20relevant%20to%20SOA.)>
+- [b-Onnx] *Open Neural Network Exchange.*  
+<<https://onnx.ai/>>
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.747.16-202503-I_PDF-E/raw.md

@@ -0,0 +1,370 @@
+
+
+# Recommendation **ITU-T F.747.16 (03/2025)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+## **Requirements for 3D machine vision-based surface defect detection service of industrial products**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.747.16
+
+# Requirements for 3D machine vision-based surface defect detection service of industrial products
+
+## Summary
+
+Recommendation ITU-T F.747.16 provides the requirements for 3D machine vision-based surface defect detection service of industrial products. Three-dimensional (3D) machine vision can obtain the complete geometric information of the real 3D scene, and the images with depth information can be used to achieve high-precision measurement, detection, positioning, reconstruction, and scene understanding. It can process various types of industrial products that cannot be processed by two-dimensional (2D) machine vision (e.g., highly reflective surfaces and low-contrast surfaces), such as electronic products and printed circuit board (PCB) surface detection, free-form surface optical mirror measurement, and measurement and detection of steel product surfaces or curved surfaces, etc.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.747.16 | 2025-03-16 | 21          | 11.1002/1000/16229 |
+
+## Keywords
+
+3D, defect detection service, machine vision.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2025
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                         | Page |
+|-----------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                           | 1    |
+| 2 References.....                                                                       | 1    |
+| 3 Definitions .....                                                                     | 1    |
+| 3.1 Terms defined elsewhere .....                                                       | 1    |
+| 3.2 Terms defined in this Recommendation.....                                           | 1    |
+| 4 Abbreviations and acronyms .....                                                      | 1    |
+| 5 Conventions .....                                                                     | 2    |
+| 6 Overview of 3D machine vision-based surface defect detection service system .....     | 2    |
+| 7 Requirements for 3D machine vision-based surface defect detection service .....       | 3    |
+| 7.1 Requirements for 3D machine vision devices and images.....                          | 3    |
+| 7.2 Requirements for service platform .....                                             | 4    |
+| 7.3 Requirements for application .....                                                  | 5    |
+| 7.4 Others .....                                                                        | 5    |
+| Appendix I – Use cases of 3D machine vision-based surface defect detection service..... | 6    |
+| I.1 Use cases of 3D high-precision detection for planes and curved surfaces.....        | 6    |
+| I.2 Measurement for flatness and geometric tolerance .....                              | 7    |
+| I.3 Detection and grading of steel plates.....                                          | 7    |
+| Bibliography.....                                                                       | 8    |
+
+
+
+# Requirements for 3D machine vision-based surface defect detection service of industrial products
+
+# 1 Scope
+
+This Recommendation presents the requirements for three-dimensional (3D) machine vision-based surface defect detection service of industrial products, especially the requirements for 3D machine vision devices and images, functional and performance requirements of service platform, as well as the presentation and application of detection results.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 algorithm** [b-ISO/IEC 11557]: A set of rules for transforming the logical representation of data.
+
+**3.1.2 machine vision** [b-ITU-T F.748.16]: Signal processing to acquire, process and interpret an image or video to support visual analysis for applications, such as automatic inspection, process control and guidance.
+
+**3.1.3 surface-defect detection** [b-ITU-T F.747.11]: Surface-defect detection refers to the identification of defects on the surface of industrial products, including the location determination, classification and measurement of different types of defects.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 three-dimensional (3D) machine vision**: Signal processing to acquire, process and interpret an image or video with depth information to support real three-dimensional (3D) scene visual analysis for applications, such as measurement, detection, positioning, reconstruction and scene understanding.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+2D Two Dimensional
+
+3C Computer, Communication and Consumer Electronics
+
+|          |                                              |
+|----------|----------------------------------------------|
+| 3D       | Three Dimensional                            |
+| CAD      | Computer Aided Design                        |
+| IMT-2020 | International Mobile Telecommunications-2020 |
+| MEC      | Multi-Access Edge Computing                  |
+| PCB      | Printed Circuit Board                        |
+| ToF      | Time of Flight                               |
+| WLAN     | Wireless Local Area Network                  |
+
+# 5 Conventions
+
+In this Recommendation:
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+- The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option, and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+# 6 Overview of 3D machine vision-based surface defect detection service system
+
+Figure 1 shows the layered framework of 3D machine vision-based surface defect detection service system. It includes device layer, network layer, service platform layer and application layer.
+
+![Figure 1 – Layered framework of 3D machine vision-based surface defect detection service system. A block diagram showing four layers: Application layer, Service platform layer, Network layer, and Device layer. Each layer contains specific functional blocks.](5860ad6bd2a2dd8d1ab12864b8f90f37_img.jpg)
+
+| Application layer      | Silicon wafer and PCB surface measurement/detection | Free-form surface optical mirror measurement/detection | Steel product surface/curved surface measurement/detection | ....                |
+|------------------------|-----------------------------------------------------|--------------------------------------------------------|------------------------------------------------------------|---------------------|
+| Service platform layer | Service display                                     |                                                        |                                                            |                     |
+|                        | Data process                                        |                                                        | Data analysis                                              |                     |
+|                        | Algorithm/measurement tool library                  |                                                        |                                                            |                     |
+| Network layer          | Cellular network (e.g., IMT-2020)                   |                                                        | Industrial Internet (e.g., optical fibre, WLAN)            |                     |
+| Device layer           | Laser                                               | Imaging devices                                        |                                                            | Auxiliary equipment |
+
+F.747.16(25)
+
+Figure 1 – Layered framework of 3D machine vision-based surface defect detection service system. A block diagram showing four layers: Application layer, Service platform layer, Network layer, and Device layer. Each layer contains specific functional blocks.
+
+**Figure 1 – Layered framework of 3D machine vision-based surface defect detection service system**
+
+The layered functional blocks of the 3D machine vision-based surface defect detection service system are as follows:
+
+- 1) **Device layer.** 3D machine vision device includes lasers, imaging devices and auxiliary equipment, online or offline to obtain 3D images of industrial product surfaces.
+- 2) **Network layer.** This layer includes cellular networks (e.g., international mobile telecommunications-2020 (IMT-2020)) and industrial Internet (e.g., optical fibre and wireless local area network (WLAN)). Its function is to send images and other auxiliary data to the service platform for processing.
+- 3) **Service platform layer.** Its functions include data processing, data analysis, service display, and the related algorithm / measurement tool libraries. The service platform can utilize various algorithms / tools to identify and classify the types and sizes of surface defects (i.e., "what is the defect", "where is the defect", and "how many defects are present"). The server platform should have sufficient computing capabilities and can provide a user-friendly graphical interactive interface to display processing results as images and graphics.
+- 4) **Application layer.** Measurement and detection applications include, but are not limited to, electronic products, printed circuit board (PCB) and semiconductor craft detection, free-form surface mirror measurement, and the measurement and detection of steel product surface or bearing and screw bolt curved surfaces. It even can go inside a container for defect detection.
+
+# 7 Requirements for 3D machine vision-based surface defect detection service
+
+## 7.1 Requirements for 3D machine vision devices and images
+
+3D machine vision devices include lasers, 3D cameras and auxiliary equipment, online or offline to obtain 3D images of industrial product surfaces.
+
+### 7.1.1 Requirements for 3D machine vision devices
+
+MVD-01: 3D machine vision devices are recommended to use one or several technologies, such as binocular technology, spectrum confocal technology, structured light technology and time of flight (ToF) technology, to obtain surface depth information of the measured object.
+
+MVD-02: It is recommended that binocular vision devices can complete calibration, obtain image pairs, match points with the same name, and calculate coordinates based on calibration parameters and phase differences.
+
+MVD-03: It is recommended that emitting structured light devices can complete calibration, obtain light stripe images and extract stripes, calculate 3D coordinates.
+
+MVD-04: It is recommended that emitting encoded light devices can complete calibration, generate encoded patterns, collect encoded images, process and decode, and calculate 3D coordinates.
+
+MVD-05: It is required that 3D machine vision devices can perform non-contact detecting, without damaging the objects / materials surface, and can match online production speed.
+
+MVD-06: It is recommended that a single 3D machine vision device plus other sensors can perceive and record the speed and direction of object movement, and use this to determine the X and Y coordinates, ensuring that the 3D point cloud data coordinates are not deformed relative to the real object.
+
+MVD-07: For multiple 3D machine vision devices, it is required that 3D machine vision devices calibrate each other and establish a unified coordinate conversion system.
+
+MVD-08: It is recommended that 3D machine vision devices support measuring transparent and highly reflective products, and can use backlight to enhance the contour features of products.
+
+MVD-09: It is recommended to use the spectrum confocal technology to obtain surface depth (object distance) information.
+
+### **7.1.2 Requirements for 3D vision images**
+
+VI-01: It is recommended that the encoding technology for 3D images includes spatial encoding, temporal encoding and colour encoding.
+
+VI-02: It is recommended that 3D point cloud data includes 3D coordinates X, Y, Z, as well as reflection intensity and colour information.
+
+VI-03: It is recommended that a three-dimensional grid is used to store and display depth images (image plus depth information).
+
+## **7.2 Requirements for service platform**
+
+The service platform is required to have sufficient computing power to process and analyse data, and be able to provide various algorithms / tools to identify and classify the types and sizes of surface defects, as well as to present surface defects on the 3D model.
+
+DP-01: It is recommended that service platform can provide algorithm tools for data preprocessing (including depth image histogram tools, missing pixel filling tools, depth image filtering tools, pixel mapping tools).
+
+DP-02: It is recommended that service platform can provide point cloud algorithms / measurement tools to complete data processing (including plane fitting tools, height measurement tools, volume measurement tools, section generation tools, point cloud position and size measurement tools, circular hole detection tools, and point cloud ellipse fitting tools).
+
+DP-03: It is recommended that service platform can provide contour algorithms / measurement tools to complete data processing (including point cloud and contour bounding box tools, contour line circle fitting tools, contour geometry measurement tools, contour position and size measurement tools, and contour area tools).
+
+DP-04: It is recommended that the service platform can recognize pits (concave defects with a certain area), scratches (narrow strip concave defects), orange peel (surface undulating defects with aggregation effect), and pockmark (point like defects with aggregation effect) on the surface of the detected object.
+
+DP-05: It is recommended that service platform concatenates and fuses point cloud data from multiple parts of a product, including aligning and concatenating defect location data, denoising, and completing the detection and analysis of the overall surface of the object.
+
+DP-06: It is recommended that service platform can divide the discontinuous areas on the surface of products (such as steel plates), identify the types of discontinuities, and classify surface defects of products based on given standards.
+
+DP-07: It is recommended that service platform be capable of completing measurements, including geometric tolerance (tolerance of form and position), flatness error and discontinuity size.
+
+DP-08: The service platform is required to provide a user-friendly graphical interactive interface to display processing results as images and graphics.
+
+DP-09: It is recommended that service platform can reconstruct a complete product 3D model based on the obtained 3D images, including the shape, size and range of defects in the 3D model; and / or, it can compare the reconstructed model with a computer aided design (CAD) model to understand the differences in contour, volume, and size.
+
+DP-10: It is recommended that service platform can replay or display statistical information on defect types and quantities and generate analysis reports.
+
+## **7.3 Requirements for application**
+
+3D machine vision system is required to quickly obtain high-precision and repeatable measurement data, be able to match the online production speed, and inspect various types of industrial products and complete the detection, positioning, identification and measurement of plane, free-form surface and curved surface defects.
+
+APP-01: It is recommended that 3D machine vision system can achieve 3D fast inspection and measurement (e.g., geometric tolerance, flatness / warpage error and discontinuity size) for precision structural components such as 3C (computer, communication and consumer electronics) products and PCB.
+
+APP-02: It is recommended that 3D machine vision system can detect planes and curved surfaces, including identifying surface dents / scratches / orange peel / pockmark; and measure surface roughness / smoothness, surface shape / contour / size, etc.
+
+APP-03: It is recommended that 3D machine vision system be capable of dividing the discontinuous areas on the surface, identifying the types of discontinuities, and grading surface defects of products based on given standards.
+
+## **7.4 Others**
+
+OTH-01: If the image data generated by 3D machine vision system is large, it is recommended to compress the data, then send it to the service platform.
+
+OTH-02: It is recommended that images generated by 3D machine vision devices be sent to the service platform for processing through wired and / or wireless networks (such as IMT-2020 networks, industrial Internet).
+
+OTH-03: It is recommended to deploy multi-access edge computing (MEC) devices to enhance real-time online processing of 3D data.
+
+## Appendix I
+
+### Use cases of 3D machine vision-based surface defect detection service
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Three-dimensional (3D) machine vision systems can quickly obtain high-precision and repeatable measurement data, and it can match the online production speed. It can detect various types of materials and industrial products, including reflective surfaces and low-contrast surfaces that cannot be processed by two-dimensional (2D) image analysis. It can complete the detection, positioning, identification and measurement of electronic products and printed circuit board (PCB) surface, free-form surface optical mirror, steel product surface / curved surface defects, etc.
+
+### I.1 Use cases of 3D high-precision detection for planes and curved surfaces
+
+Figure I.1 shows a schematic diagram of 3D detection, along with an example of the depth information of automotive glass surface (right image). Different surface depths may be displayed in different ways (e.g., in different colours) on the screen so that people can see the range and location of defects. Figure I.2 presents more examples of 3D machine vision measurement.
+
+![Figure I.1: Schematic diagram of 3D detection and an example of surface depth information. The left side shows a schematic of a laser and camera setup for 3D detection on a curved glass surface. The right side shows a 3D depth map of an automotive glass surface with a color scale indicating depth.](dd330f8b8f6c16eae20c3a676b4eb804_img.jpg)
+
+The figure consists of two parts. The left part is a schematic diagram of a 3D detection setup. It shows a 'Laser' projecting a plane onto an 'Upper surface' of a 'Curved glass'. A 'Camera' is positioned to capture the laser line. Coordinate axes are labeled:  $Xl, Yl, Zl$  for the laser and  $Xc, Yc, Zc$  for the camera. The right part is a 3D depth map of a curved glass surface, with a color scale on the left ranging from 1 (blue) to 14 (red). The map shows a wavy surface with varying depths. A label 'F.747.16(25)' is present in the bottom right corner.
+
+Figure I.1: Schematic diagram of 3D detection and an example of surface depth information. The left side shows a schematic of a laser and camera setup for 3D detection on a curved glass surface. The right side shows a 3D depth map of an automotive glass surface with a color scale indicating depth.
+
+**Figure I.1 – Schematic diagram of 3D detection and an example of surface depth information**
+
+![Figure I.2: Examples of 3D machine vision measurement. The figure shows three different 3D surface measurements: a flat surface with a color gradient, a curved surface with a color gradient, and a complex irregular shape with a color gradient.](624d9669faa18991d525fea5f0e03269_img.jpg)
+
+The figure displays three examples of 3D machine vision measurements. The first example on the left shows a flat surface with a color gradient representing depth. The second example in the middle shows a curved surface with a color gradient. The third example on the right shows a complex, irregular shape (possibly a mechanical part) with a color gradient. All three plots have axes indicating spatial dimensions.
+
+Figure I.2: Examples of 3D machine vision measurement. The figure shows three different 3D surface measurements: a flat surface with a color gradient, a curved surface with a color gradient, and a complex irregular shape with a color gradient.
+
+**Figure I.2 – Examples of 3D machine vision measurement**
+
+Other use cases include high-precision measurement of the depth and spacing of screw thread, micrometer-level measurement of the optical free-form surface (e.g., mirror and lens), and measurement of irregular shape parts to determine whether these products meet the design requirements, whether they have defects, as well as the size and location of defects. The measurement
+
+accuracy can range from 1-50  $\mu\text{m}$ , X-axis resolution can range 1-10  $\mu\text{m}$ , Z-axis resolution can range 1-5  $\mu\text{m}$ , and the repeated positioning accuracy of the displacement table can be less than 1  $\mu\text{m}$ .
+
+### I.2 Measurement for flatness and geometric tolerance
+
+The service system can perform 3D fast online flatness and geometric tolerance measurement for 3C (computer, communication and consumer electronics) and PCB products. The following Figure I.3 presents a schematic diagram of metal card holder flatness and geometric tolerance measurement.
+
+![Figure I.3: Three images showing 3D point cloud data for 3C product components. The first image shows a rectangular metal frame. The second image shows a complex electronic component with circular features. The third image shows a dense grid of points on a flat surface, likely a PCB or metal plate, with a color scale indicating height variations.](0cc86fe8fc37b0edc9581f2af9459a52_img.jpg)
+
+Figure I.3: Three images showing 3D point cloud data for 3C product components. The first image shows a rectangular metal frame. The second image shows a complex electronic component with circular features. The third image shows a dense grid of points on a flat surface, likely a PCB or metal plate, with a color scale indicating height variations.
+
+**Figure I.3 – Examples of detection for 3C product components**
+
+### I.3 Detection and grading of steel plates
+
+By using multiple cameras side by side, surface point cloud data of larger steel plate can be obtained, and this point cloud data can be concatenated and fused to be transformed into a 3D model of the steel plate. The appearance information of the steel plate, including dimensions, natural deformation, and surface discontinuity information, can be visually observed (as shown in Figure I.4), with a measurement accuracy of 0.1 mm. The service platform can divide the discontinuous areas on the surface of steel plates, identify the types of discontinuities, and grade surface defects of products based on given standards.
+
+![Figure I.4: Two images showing 3D appearance information of a steel plate. The left image is a 3D surface plot with a color scale for height, showing a relatively flat surface with some minor deformation. The right image is a surface point cloud image showing a grid of points on a steel plate, with a small depression or defect visible.](c222a9006d6d60a8d81e6ffbfc0e74ad_img.jpg)
+
+Figure I.4: Two images showing 3D appearance information of a steel plate. The left image is a 3D surface plot with a color scale for height, showing a relatively flat surface with some minor deformation. The right image is a surface point cloud image showing a grid of points on a steel plate, with a small depression or defect visible.
+
+**Figure I.4 – Examples of 3D appearance information of steel plate and a surface point cloud image**
+
+## Bibliography
+
+- [b-ITU-T F.747.11] Recommendation ITU-T F.747.11 (2022), *Requirements for intelligent surface-defect detection service in industrial production lines.*
+- [b-ITU-T F.748.16] Recommendation ITU-T F.748.16 (2022), *Requirements for applications and services in smart manufacturing based on machine vision.*
+- [b-ISO/IEC 11557] ISO/IEC 11557:1992, *Information technology – 3,81 mm wide magnetic tape cartridge for information interchange – Helical scan recording – DDS-DC format using 60 m and 90 m length tapes.*
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.748.11-202008-I_PDF-E/raw.md

@@ -0,0 +1,485 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**F.748.11**
+
+(08/2020)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Multimedia services
+
+---
+
+**Metrics and evaluation methods for a deep  
+neural network processor benchmark**
+
+Recommendation ITU-T F.748.11
+
+# ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multdestination satellite services          | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | F.400–F.499        |
+| <b>DIRECTORY SERVICES</b>                                       | F.500–F.549        |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | F.600–F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | F.800–F.849        |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | F.850–F.899        |
+| <b>ACCESSIBILITY AND HUMAN FACTORS</b>                          | F.900–F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.748.11
+
+# Metrics and evaluation methods for a deep neural network processor benchmark
+
+## Summary
+
+Recommendation ITU-T F.748.11 provides the benchmarking framework, evaluation metrics and methods, and application scenarios for deep neural network processors operating training and inference tasks.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T F.748.11 | 2020-08-13 | 16          | <a href="http://handle.itu.int/11.1002/1000/14329">11.1002/1000/14329</a> |
+
+## Keywords
+
+Benchmark, cloud, deep neural network processor, metrics, mobile.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2020
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                    | Page |
+|------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                      | 1    |
+| 2 References.....                                                                  | 1    |
+| 3 Definitions .....                                                                | 1    |
+| 3.1 Terms defined elsewhere .....                                                  | 1    |
+| 3.2 Terms defined in this Recommendation.....                                      | 1    |
+| 4 Abbreviations and acronyms .....                                                 | 2    |
+| 5 Conventions .....                                                                | 2    |
+| 6 Overview of a deep neural network processor benchmark.....                       | 3    |
+| 6.1 Evaluation object .....                                                        | 3    |
+| 6.2 Evaluation principle.....                                                      | 3    |
+| 7 Architecture framework of the deep neural network processor benchmark.....       | 3    |
+| 7.1 Workload .....                                                                 | 4    |
+| 7.2 AI framework .....                                                             | 4    |
+| 7.3 Hardware acceleration SDK .....                                                | 4    |
+| 7.4 Processor hardware system.....                                                 | 4    |
+| 8 Benchmark metrics and evaluation methods for AI chip under training tasks.....   | 5    |
+| 8.1 Metrics .....                                                                  | 5    |
+| 8.2 Benchmark specification .....                                                  | 5    |
+| 9 Benchmark metrics and evaluation methods for AI chip under inference tasks ..... | 5    |
+| 9.1 Metrics .....                                                                  | 5    |
+| 9.2 Benchmark specification .....                                                  | 6    |
+| 10 Benchmark application scenarios .....                                           | 7    |
+| Appendix I – Reference implementations of benchmark application scenarios.....     | 8    |
+
+
+
+# Recommendation ITU-T F.748.11
+
+## Metrics and evaluation methods for a deep neural network processor benchmark
+
+# 1 Scope
+
+This Recommendation provides the benchmarking framework, evaluation metrics and methods, and application scenarios for operating training and inference tasks.
+
+It addresses the following subjects:
+
+- a) Evaluation method of a deep neural network processor benchmark;
+- b) Architecture framework of the deep neural network processor benchmark;
+- c) Metrics of the deep neural network processor benchmark;
+- d) Benchmark application scenarios of the deep neural network processor benchmark;
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T Y.3172] Recommendation ITU-T Y.3172 (2019), *Architectural framework for machine learning in future networks including IMT-2020*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 machine learning (ML)** [ITU-T Y.3172]: Processes that enable a computational system to understand data and gain knowledge from it without necessarily being explicitly programmed.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 benchmark:** Benchmark is an evaluation method with a long-term application in the entire computer field. Example: As computer architecture advanced, it became more difficult to compare the performance of various computer systems simply by looking at their specifications. Therefore, tests were developed that allowed comparison of different architectures (i.e., providing benchmarks).
+
+**3.2.2 deep neural network processor:** A deep neural network processor is the kind of processor that could accelerate the computing process regarding a deep neural network.
+
+**3.2.3 workload:** Workload is the benchmark test task for measuring and evaluating artificial intelligence chips, that is, the benchmark test program containing a specific AI task.
+
+**3.2.4 test data set:** A subset of the data set which is used to test the model after the model that has been initially verified by the validation data set.
+
+**3.2.5 model operations:** Model operations are the theoretical amount of operations in deep neural networks. For float operations, the unit is the floating point of operations (FLOPs), and for integer operations, the unit is operations (OPs).
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                         |
+|-------|-----------------------------------------|
+| AI    | Artificial Intelligence                 |
+| API   | Application Programming Interface       |
+| ASIC  | Application-Specific Integrated Circuit |
+| BLEU  | Bilingual Evaluation Understudy         |
+| CNN   | Convolutional Neural Network            |
+| CPU   | Central Processing Unit                 |
+| DNN   | Deep neural network                     |
+| DSP   | Digital Signal Processing               |
+| DUT   | Device under test                       |
+| FLOPs | Floating Point of Operations            |
+| FPGA  | Field Programmable Gate Array           |
+| FPS   | Frame Per Second                        |
+| GPU   | Graphic Processor Unit                  |
+| MAC   | Multiply and Accumulate                 |
+| mAP   | Mean Average Precision                  |
+| NMS   | Non-Maximum Suppression                 |
+| NPU   | Neural Processing Unit                  |
+| OPs   | Operations                              |
+| PSNR  | Peak Signal to Noise Ratio              |
+| ROC   | Receiver Operating Characteristic       |
+| SDK   | Software Development Kit                |
+
+# 5 Conventions
+
+The following conventions are used in this Recommendation:
+
+- The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+- The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+# 6 Overview of a deep neural network processor benchmark
+
+## 6.1 Evaluation object
+
+The evaluation object can be a processor for training and inference tasks at the cloud side, such as an acceleration card, an all-in-one, etc. Or a processor for inference tasks at the mobile side, such as a development board, a mobile phone, and a dedicated chip for applications such as security, autonomous driving, and smart speakers.
+
+## 6.2 Evaluation principle
+
+### 6.2.1 Practicality
+
+Benchmarking methods should be able to produce positive results.
+
+### 6.2.2 Fairness
+
+Benchmarking methods should provide a fair comparison by specifying rules and metrics and be based on objective scientific test data during the evaluation process.
+
+### 6.2.3 Reproducibility
+
+When the same detected quantity is detected in different detection environments, the consistency of the measurement results is ensured.
+
+### 6.2.4 Evaluation mechanism
+
+The benchmarking program focuses on the performance of the processor when operating different training/inference tasks using a complete neural network under specified metrics.
+
+### 6.2.5 Test environment
+
+The benchmark test environment consists of three parts as shown in Figure 6-1, which are respectively the test computer, power consumption monitoring and the device under test (DUT). The test computer is connected through the DUT interface. The power software test tool analyses the DUT's feedback's current and voltage results. Benchmark tools calculate the relevant evaluation metrics.
+
+![Diagram of the benchmark test environment showing the connections between a Power consumption monitoring unit, a Computer, and a DUT.](5a24ac755b962fd5f0183f13de0726de_img.jpg)
+
+The diagram illustrates the benchmark test environment. It features three main components: a 'Power consumption monitoring' unit, a 'Computer' (containing 'Power software test tool + benchmark tool'), and a 'DUT' (Device Under Test). The 'Power consumption monitoring' unit is connected to the 'DUT' via a 'Power cable' and to the 'Computer' via a data line. The 'DUT' has 'Negative' and 'Positive' terminals. A 'Data transmission' line connects the 'Computer' to the 'DUT'. The label 'F.748.11(20)\_F6-1' is present in the bottom right corner of the diagram.
+
+Diagram of the benchmark test environment showing the connections between a Power consumption monitoring unit, a Computer, and a DUT.
+
+**Figure 6-1 – Benchmark test environment**
+
+# 7 Architecture framework of the deep neural network processor benchmark
+
+The benchmarking framework is divided into three layers, as shown in Figure 7-1. These are respectively from the bottom to the top: 1) processor hardware system, 2) hardware acceleration software development kit (SDK), 3) artificial intelligence (AI) framework.
+
+![Figure 7-1: Architecture framework of the deep neural network processor benchmark. The diagram shows a flow from 'Input: Workload' to a box containing 'AI framework' and 'Hardware acceleration SDK', which then points to 'Processor hardware system'. An arrow from the processor points to an 'Output: Metrics' box containing Latency, Throughput, Power, Energy efficiency, Accelerator utilization, and ellipsis. The label F.748.11(20)_F7-1 is at the bottom right.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+```
+
+graph TD
+    Input[Input: Workload] --> Framework[AI framework  
+Hardware acceleration SDK]
+    Framework --> Processor[Processor hardware system]
+    Processor --> Metrics[Output: Metrics  
+Latency  
+Throughput  
+Power  
+Energy efficiency  
+Accelerator utilization  
+...]
+  
+```
+
+F.748.11(20)\_F7-1
+
+Figure 7-1: Architecture framework of the deep neural network processor benchmark. The diagram shows a flow from 'Input: Workload' to a box containing 'AI framework' and 'Hardware acceleration SDK', which then points to 'Processor hardware system'. An arrow from the processor points to an 'Output: Metrics' box containing Latency, Throughput, Power, Energy efficiency, Accelerator utilization, and ellipsis. The label F.748.11(20)\_F7-1 is at the bottom right.
+
+**Figure 7-1 – Architecture framework of the deep neural network processor benchmark**
+
+As shown in Figure 7-2, according to the deployment location, a benchmark can be divided into cloud side and edge/mobile side and according to the task, it can be divided into training phase and inference phase.
+
+![Figure 7-2: Classification of deep neural network processor benchmark. The diagram shows 'DNN processor benchmark' branching into 'Edge/mobile' and 'Server/cloud'. 'Edge/mobile' leads to 'Inference'. 'Server/cloud' leads to both 'Inference' and 'Training'. The label F.748.11(20)_F7-2 is at the bottom right.](e6df2733626a85205c1db682e6259c46_img.jpg)
+
+```
+
+graph LR
+    DNN[DNN processor benchmark] --> Edge[Edge/mobile]
+    DNN --> Server[Server/cloud]
+    Edge --> Inference1[Inference]
+    Server --> Inference2[Inference]
+    Server --> Training[Training]
+  
+```
+
+F.748.11(20)\_F7-2
+
+Figure 7-2: Classification of deep neural network processor benchmark. The diagram shows 'DNN processor benchmark' branching into 'Edge/mobile' and 'Server/cloud'. 'Edge/mobile' leads to 'Inference'. 'Server/cloud' leads to both 'Inference' and 'Training'. The label F.748.11(20)\_F7-2 is at the bottom right.
+
+**Figure 7-2 – Classification of deep neural network processor benchmark**
+
+## 7.1 Workload
+
+Workload consists of test cases that use neural network models to complete training or inference tasks in specified test scenarios.
+
+## 7.2 AI framework
+
+The AI framework is a software framework for implementing relevant artificial intelligence models. It includes training frameworks such as TensorFlow, PyTorch, Caffe, PaddlePaddle and Theano, and inference frameworks such as MACE, SNPE, NCNN, TensorFlow Lite, Caffe2go, MDL, Core ML, and others. These frameworks allow us to build deep learning models to complete training or inference tasks.
+
+## 7.3 Hardware acceleration SDK
+
+The hardware acceleration SDK can support the AI framework upwards, and provide the central processing unit (CPU), graphic processor unit (GPU), digital signal processing (DSP), and neural processing unit (NPU) with required hardware resources for scheduling and use.
+
+## 7.4 Processor hardware system
+
+The processor hardware system can contain physical devices for artificial intelligence computing, including chips such as CPU, GPU, application-specific integrated circuit (ASIC), field programmable gate array (FPGA), etc., as well as computing servers and mobile terminal devices.
+
+# 8 Benchmark metrics and evaluation methods for AI chip under training tasks
+
+## 8.1 Metrics
+
+### 8.1.1 Training time
+
+The training time is generally defined as the time for training a model on a specific data set to achieve the target accuracy, excluding pre-processing and model loading time.
+
+### 8.1.2 Accuracy
+
+Accuracy here refers to the accuracy related to the training set. For specific application scenarios and data sets, given the network structure and hyper-parameter configuration, the accuracy metric is used to check whether the training can reach the specified accuracy after a certain number of iterations (training time).
+
+## 8.2 Benchmark specification
+
+### 8.2.1 Test data set
+
+The test data set discloses the proportion of the training set and the test data set and the data pre-processing method.
+
+### 8.2.2 Model
+
+It is required to unify the hyper-parameters, weights' initialization and the format of weights (fp64, fp32, fp16).
+
+### 8.2.3 Reference implementation
+
+Table 8-1 provides test scenarios, test data sets, target accuracy, and reference models for training benchmarks. All these scenarios are recommended while provided with a training benchmark.
+
+**Table 8-1 – Test scenarios for training**
+
+| Test scenarios | Test data set      | Target accuracy                     | Model       |
+|----------------|--------------------|-------------------------------------|-------------|
+| 10.1           | ImageNet (224x224) | 74.9% Top-1 Accuracy                | ResNet_50   |
+| 10.2           | COCO 2017          | 23% mAP                             | SSD         |
+| 10.2           | COCO 2017          | 0.377 Box min AP, 0.339 Mask min AP | Mask R-CNN  |
+| 10.6           | WMT English-German | 25.0 BLEU                           | Transformer |
+
+## 9 Benchmark metrics and evaluation methods for AI chip under inference tasks
+
+## 9.1 Metrics
+
+### 9.1.1 Inference latency
+
+Inference latency refers to the time that accelerator/processor completes the inference with respect to one sample for a given application scenario with a specific batch size, excluding pre-process and post-process time.
+
+### 9.1.2 Throughput
+
+Throughput is the number of input data samples that is being processed per second. For an image processing task, the unit of throughput is frames per second (FPS).
+
+### 9.1.3 Power consumption
+
+Power consumption refers to the average power consumption of the DUT in the process of inference.
+
+### 9.1.4 Energy efficiency
+
+Energy efficiency refers to the ratio of the throughput with a specific network to the power consumption of the task performed in a given application scenario.
+
+### 9.1.5 Accelerator utilization
+
+Accelerator utilization refers to the ratio of the actual amount of model operations to the theoretical peak performance under the given application scenario.
+
+Accelerator utilization = (throughput \* model operations) / theoretical peak performance.
+
+Taking the convolutional neural network (CNN) as an example, model operations= MAC\*2.
+
+### 9.1.6 Accuracy
+
+The accuracy of the model inference is related to specific tasks and evaluation metrics. See clause 10 for details.
+
+## 9.2 Benchmark specification
+
+### 9.2.1 Test system environment
+
+According to the operating system the test system environment is an environment supported by the device under test (DUT).
+
+### 9.2.2 Acceleration SDK
+
+The acceleration SDK provides the neural network acceleration engine and its detailed description. It provides interface functions including initialization Init (), pre-processing PreProcess (), loading model LoadModel (), running Run (), unloading model UnloadModel () and post processing PostProcess ().
+
+### 9.2.3 Model information
+
+Provides relevant information including model categories, original accuracy, data set, input and output node names, the mean of pre-processing and normalized parameters, tensor information (input and output), channel information (RGB / BGR), and data format (NHWC, etc.).
+
+### 9.2.4 Reference implementation
+
+Table 9-1 provides test scenarios, test data sets, target accuracy, and reference models for an inference benchmark. All these scenarios are recommended while doing a training benchmark.
+
+**Table 9-1– Test scenarios for inference**
+
+| Test scenarios | Test data | Model                                                           |
+|----------------|-----------|-----------------------------------------------------------------|
+| 10.1           | ImageNet  | ResNet_50, ResNet_101, Inception_v4, MobileNet_v1, MobileNet_v2 |
+| 10.2           | COCO 2017 | Faster-RCNN (with FPN), Yolo V3, SSD                            |
+| 10.3           | VOC2012   | Deeplabv3+                                                      |
+| 10.4           | 2017CVPR  | VDSR                                                            |
+| 10.5           | LFW       | DeepID3                                                         |
+
+# 10 Benchmark application scenarios
+
+Deep learning technologies are most commonly applied within vision, language/audio, and commerce. The application scenario indicates specific tasks developed based on these three application areas. For vision, the application scenarios include classification, recognition, and detection, semantic segmentation, etc. For language and audio, application scenarios could be machine translation and speech recognition. For commerce, the recommendation is the most well-known application scenario. Table 10-1 shows the typical application scenarios with related datasets and reference implementations, which are recommended when conducting benchmark test.
+
+**Table 10-1 – Benchmark application scenarios**
+
+| Area           | No.  | Application scenarios | Dataset          | Reference implementation model | Accuracy            |
+|----------------|------|-----------------------|------------------|--------------------------------|---------------------|
+| Vision         | 10.1 | Image classification  | ImageNet         | ResNet/Inception/MobileNet     | Prediction accuracy |
+|                | 10.2 | Object detection      | COCO2017/VOC2012 | SSD/Mask R-CNN/YOLO            | mAP, NMS            |
+|                | 10.3 | Segmentation          | VOC2012          | Deeplabv3+/FCN                 | mIoU                |
+|                | 10.4 | Super-Resolution      | DIV2K            | VGG19/VDSR                     | PSNR,SSIM           |
+|                | 10.5 | Face recognition      | LFW              | VGG-16-Face CNN (224x224)      | Rank1,ROC           |
+| Language/Audio | 10.6 | Translation           | WMT Eng-Germ     | Transformer                    | BLEU                |
+|                | 10.7 | Speech recognition    | LibriSpeech      | Deep Speech 2                  | WER<br>Perplexity   |
+| Commerce       | 10.8 | Recommendation        | MovieLens-20M    | NCF                            | Prediction accuracy |
+
+## Appendix I
+
+### Reference implementations of benchmark application scenarios
+
+Table I.1 gives a reference implementation of benchmark application scenarios.
+
+**Table I.1 – Benchmark test use cases**
+
+| No.  | Application scenarios | Dataset  | Source                                                                                            | Model (input size)        | Source                                                                                                                                                            |
+|------|-----------------------|----------|---------------------------------------------------------------------------------------------------|---------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 10.1 | Image classification  | ImageNet | <a href="http://www.image-net.org/download-images">http://www.image-net.org/download-images</a>   | ResNet_50 (224x224)       | <a href="https://github.com/KaimingHe/deep-residual-networks">https://github.com/KaimingHe/deep-residual-networks</a>                                             |
+|      |                       |          |                                                                                                   | ResNet-101 (224x224)      | <a href="https://github.com/KaimingHe/deep-residual-networks">https://github.com/KaimingHe/deep-residual-networks</a>                                             |
+|      |                       |          |                                                                                                   | Inception-v3 (299x299)    | <a href="https://github.com/tensorflow/models/tree/master/research/slim">https://github.com/tensorflow/models/tree/master/research/slim</a>                       |
+|      |                       |          |                                                                                                   | MobileNet-v2 (224x224)    | <a href="https://github.com/shicai/MobileNet-Caffe">https://github.com/shicai/MobileNet-Caffe</a>                                                                 |
+| 10.2 | Object detection      | VOC2012  | <a href="http://host.robots.ox.ac.uk/pascal/VOC/">http://host.robots.ox.ac.uk/pascal/VOC/</a>     | ssd_mobilenetv1 (300x300) | <a href="https://github.com/FreeApe/VGG-or-MobileNet-SSD">https://github.com/FreeApe/VGG-or-MobileNet-SSD</a>                                                     |
+|      |                       |          |                                                                                                   | YOLOv3 (320x320)          | <a href="https://github.com/eric612/MobileNet-YOLO">https://github.com/eric612/MobileNet-YOLO</a>                                                                 |
+| 10.3 | Segmentation          | VOC2012  | <a href="http://host.robots.ox.ac.uk/pascal/VOC/">http://host.robots.ox.ac.uk/pascal/VOC/</a>     | FCN (500x500)             | <a href="https://github.com/shelhamer/fcn.berkeleyvision.org/tree/master/voc-fcn8s">https://github.com/shelhamer/fcn.berkeleyvision.org/tree/master/voc-fcn8s</a> |
+| 10.4 | Super-Resolution      | DIV2K    | <a href="https://data.vision.ee.ethz.ch/cvl/DIV2K/">https://data.vision.ee.ethz.ch/cvl/DIV2K/</a> | VDSR (256x256)            | <a href="https://github.com/huangzehao/caffe-vdsr">https://github.com/huangzehao/caffe-vdsr</a>                                                                   |
+| 10.5 | Face recognition      | LFW      | <a href="http://viswww.cs.umass.edu/lfw/">http://viswww.cs.umass.edu/lfw/</a>                     | VGG-16-Face CNN (224x224) | <a href="http://www.robots.ox.ac.uk/~vgg/software/vgg_face/">http://www.robots.ox.ac.uk/~vgg/software/vgg_face/</a>                                               |
+
+**Table I.1 – Benchmark test use cases**
+
+| <b>No.</b> | <b>Application scenarios</b> | <b>Dataset</b> | <b>Source</b>                                                                                     | <b>Model (input size)</b> | <b>Source</b>                                                                                     |
+|------------|------------------------------|----------------|---------------------------------------------------------------------------------------------------|---------------------------|---------------------------------------------------------------------------------------------------|
+| 10.6       | Translation                  | WMT Eng-Germ   | <a href="http://www.statmt.org">http://www.statmt.org</a>                                         | Transformer               | <a href="https://github.com/Kyubyong/transformer">https://github.com/Kyubyong/transformer</a>     |
+| 10.7       | Speech recognition           | Libri Speech   | <a href="http://www.openslr.org/12/">http://www.openslr.org/12/</a>                               | Deep Speech 2             | <a href="https://github.com/yao-matrix/deepSpeech2">https://github.com/yao-matrix/deepSpeech2</a> |
+| 10.8       | Recommendation               | Movie Lens-20M | <a href="https://grouplens.org/datasets/movielens/">https://grouplens.org/datasets/movielens/</a> | NCF                       | <a href="https://github.com/guoyang9/NCF">https://github.com/guoyang9/NCF</a>                     |
+
+
+
+
+
+# SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/F/T-REC-F.748.22-202309-I_PDF-E/raw.md

@@ -0,0 +1,441 @@
+
+
+# Recommendation**ITU-T F.748.22 (09/2023)**
+
+SERIES F: Non-telephone telecommunication services  
+Multimedia services
+
+---
+
+## **Functional architecture for feature-based distributed intelligent systems**
+
+![ITU logo](390120de4fe440c42fea8154fcaad334_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font overlaid on the globe.
+
+ITU logo
+
+## ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.748.22
+
+## Functional architecture for feature-based distributed intelligent systems
+
+## Summary
+
+Recommendation ITU-T F.748.22 defines the architecture, the functional entities, and the reference points for feature-based distributed intelligent systems.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.748.22 | 2023-09-13 | 16          | 11.1002/1000/15621 |
+
+## Keywords
+
+Feature, functional architecture, functional entity, intelligent system, reference point.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                     | Page |
+|-------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                       | 1    |
+| 2 References.....                                                                   | 1    |
+| 3 Definitions .....                                                                 | 1    |
+| 3.1 Terms defined elsewhere .....                                                   | 1    |
+| 3.2 Terms defined in this Recommendation.....                                       | 1    |
+| 4 Abbreviations and acronyms .....                                                  | 1    |
+| 5 Conventions .....                                                                 | 2    |
+| 6 Overview of feature-based intelligent applications .....                          | 2    |
+| 7 A functional architecture for feature-based distributed intelligent systems ..... | 3    |
+| 8 Functional entities.....                                                          | 4    |
+| 8.1 Front-end function set.....                                                     | 4    |
+| 8.2 Data processing function set.....                                               | 5    |
+| 8.3 Algorithm function set.....                                                     | 5    |
+| 8.4 Service control function set .....                                              | 6    |
+| 8.5 Operation function set .....                                                    | 6    |
+| 8.6 Management function set .....                                                   | 6    |
+| 8.7 Security function set.....                                                      | 6    |
+| 8.8 Development function set.....                                                   | 7    |
+| 8.9 Applications.....                                                               | 7    |
+| 9 Reference points .....                                                            | 8    |
+| 9.1 Reference point A1 .....                                                        | 8    |
+| 9.2 Reference point A2.....                                                         | 8    |
+| 9.3 Reference point A3.....                                                         | 8    |
+| 9.4 Reference point A4.....                                                         | 8    |
+| 9.5 Reference point A5.....                                                         | 8    |
+| 9.6 Reference point A6.....                                                         | 8    |
+| 9.7 Reference point A7.....                                                         | 8    |
+| 9.8 Reference point A8.....                                                         | 9    |
+| 9.9 Reference point A9.....                                                         | 9    |
+| Bibliography.....                                                                   | 10   |
+
+
+
+# Recommendation ITU-T F.748.22
+
+## Functional architecture for feature-based distributed intelligent systems
+
+## 1 Scope
+
+This Recommendation defines the architecture, the reference points and the functional entities and their relationships in feature-based distributed intelligent systems (FDIS).
+
+The scope of this Recommendation includes:
+
+- The architecture for feature-based distributed intelligent systems.
+- The functional entities and their relationships with feature-based distributed intelligent systems.
+- The reference points in feature-based distributed intelligent systems.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T F.748.11] Recommendation ITU-T F.748.11 (2020), *Metrics and evaluation methods for a deep neural network processor benchmark*.
+
+[ITU-T F.748.21] Recommendation ITU-T F.748.21 (2022), *Requirements and framework for feature-based distributed intelligent systems*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 front-end equipment** [b-ITU-T K.142]: Outdoor camera and associated ancillary equipment.
+
+**3.1.2 premises unit** [b-ITU-T F.743]: A device located at the remote part of a video surveillance system and used to capture multimedia information (such as audio, video, image, alarm signal, etc.) from a surveilled object.
+
+### 3.2 Terms defined in this Recommendation
+
+None.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                                   |
+|-----|-----------------------------------|
+| API | Application Programming Interface |
+| ASF | Audio Sensor Function             |
+| DPF | Data Preparation Function         |
+
+|      |                                               |
+|------|-----------------------------------------------|
+| DPPF | Data Preprocessing Function                   |
+| DSF  | Data Storage Function                         |
+| FCF  | Feature Compression Function                  |
+| FDF  | Feature Decoding Function                     |
+| FDIS | Feature-based Distributed Intelligent Systems |
+| FEF  | Feature Encoding Function                     |
+| FXF  | Feature Extraction Function                   |
+| IAAF | Intelligent Audio Algorithm Function          |
+| ITS  | Intelligent Traffic Systems                   |
+| IVAF | Intelligent Video Algorithm Function          |
+| NLP  | Natural Language Processing                   |
+| VSF  | Video Sensor Function                         |
+
+## 5 Conventions
+
+In this Recommendation:
+
+Function set: In the context of FDIS architecture, "function set" are defined as a collection of functionalities. It is represented by the following symbol:
+
+![A rounded rectangular box containing the text 'Function Set'.](35a7554182eb055209552843f341a1ae_img.jpg)
+
+A rounded rectangular box containing the text 'Function Set'.
+
+Function: In the context of FDIS architecture, a "function" is defined as a group of functionalities that has not been further subdivided at the level of detail described in this Recommendation. It is represented by the following symbol:
+
+![A rectangular box containing the text 'Function'.](5860ad6bd2a2dd8d1ab12864b8f90f37_img.jpg)
+
+A rectangular box containing the text 'Function'.
+
+## 6 Overview of feature-based intelligent applications
+
+Feature-based distributed intelligent systems (FDIS) extract and transmit features instead of original data, i.e., video, audio, text, point cloud, etc. Compared to intelligent systems that are based on original multimedia data, which require a large amount of storage and transmission bandwidth and offer limited technological solutions that use multimedia coding to reduce data volume, FDIS could save bandwidth by extracting only the effective information from multimedia data.
+
+In some latency sensitive intelligent systems, i.e., autonomous driving and industrial detection and control, it is crucial to process the data in real-time. Using features in addition to original data might allow fast searching and other artificial intelligence (AI) tasks. FDIS is able to reduce the latency in some scenarios.
+
+Feature-based intelligent applications are applications that utilize feature data extracted from real-world scenarios for machine learning and processing. FDIS is a type of distributed intelligence system.
+
+## 7 A functional architecture for feature-based distributed intelligent systems
+
+![Figure 1: A functional architecture for feature-based distributed intelligent systems. The diagram shows a layered structure with various function sets and their interconnections. At the top, four dashed boxes represent 'Applications': Intelligent traffic, Smart manufacturing, Smart city, and Smart agriculture. Below this, a central vertical spine connects several function sets. A4 (Service control function set) contains Data storage function, Industrial camera SDK, and Neural network algorithm models. A3 (Algorithm function set) contains Intelligent video algorithm function, Intelligent audio algorithm function, and Natural language processing function. A2 (Data processing function set) contains Feature decoding function, Data storage function, and Data preparation function. A1 (Front-end function set) contains Video sensor function, Audio sensor function, Data preprocessing function, Feature encoding function, Feature extraction function, and Feature compression function. On the left, A6 (Operation function set) contains Data transformation, Data aggregation, Feature selection, and Operation function set. A9 (Development function set) contains Model training, Model validation, Model compression, Model visualization, and Development function set. On the right, A5 (Security function set) contains Data encryption, Data authentication, Data access control, Data integrity checks, Network security, Security monitoring, Data masking, and Data security auditing. A7 (Management function set) contains User management, Resource management, System monitoring, and System log. Arrows indicate data flow and control between these sets, with labels A1 through A9.](acfc53eca625d62b38aa2563efa95c3e_img.jpg)
+
+Figure 1: A functional architecture for feature-based distributed intelligent systems. The diagram shows a layered structure with various function sets and their interconnections. At the top, four dashed boxes represent 'Applications': Intelligent traffic, Smart manufacturing, Smart city, and Smart agriculture. Below this, a central vertical spine connects several function sets. A4 (Service control function set) contains Data storage function, Industrial camera SDK, and Neural network algorithm models. A3 (Algorithm function set) contains Intelligent video algorithm function, Intelligent audio algorithm function, and Natural language processing function. A2 (Data processing function set) contains Feature decoding function, Data storage function, and Data preparation function. A1 (Front-end function set) contains Video sensor function, Audio sensor function, Data preprocessing function, Feature encoding function, Feature extraction function, and Feature compression function. On the left, A6 (Operation function set) contains Data transformation, Data aggregation, Feature selection, and Operation function set. A9 (Development function set) contains Model training, Model validation, Model compression, Model visualization, and Development function set. On the right, A5 (Security function set) contains Data encryption, Data authentication, Data access control, Data integrity checks, Network security, Security monitoring, Data masking, and Data security auditing. A7 (Management function set) contains User management, Resource management, System monitoring, and System log. Arrows indicate data flow and control between these sets, with labels A1 through A9.
+
+F.748.22(23)
+
+**Figure 1 – A functional architecture for feature-based distributed intelligent systems**
+
+A functional architecture for FDIS, as shown in Figure 1, is composed of a front-end function set, a data processing function set, an algorithm function set, applications, a service control function set, an operation function set, a management function set, and a security function set.
+
+The front-end function set (normally mapping to the front-end equipment) has the ability to capture, process, and compress the signal. The front-end function set also has the ability to pre-process, extract features, and encode data.
+
+The data processing function set provides the ability to decode data, store data, and prepare data.
+
+The algorithm function set provides algorithms for machine tasks, data storage, and data evaluation.
+
+The development function set provides the ability of model training, model validation, model compression, and model visualization.
+
+The applications provide the capability to implement machine tasks from the original data and/or from the feature data.
+
+The service control function set provides abilities for users to control the service of the FDIS.
+
+The operation function set provides the ability to manage and monitor the operation status of the system.
+
+The management function set provides the ability to manage different parts of the feature-based distributed intelligent system.
+
+The security function set provides capabilities for system security.
+
+## **8 Functional entities**
+
+### **8.1 Front-end function set**
+
+The front-end function set (normally mapping to the front-end equipment) has the ability to capture, process, and compress the signal. Sensors capture and output the digital signals. Based on the target needs, users can choose which pre-processing methods and which kinds of features to be used for the captured signal. The features are then extracted accordingly and then encoded and sent to the application or service via a network by the front-end equipment. The front-end function set includes the video sensor function, audio sensor function, data preprocessing function, feature extraction function, feature compression function, and feature encoding function.
+
+The video sensor function (VSF) captures the visual signal from the real world in raw format. The VSF could be a camera, camera system, or other imaging device that enables it to detect motion and capture it as a series of still images or video footage. Features could be extracted to detect motion of people or objects without detecting the identity of the people, alerting a user to potential security risks or allowing them to capture footage of an event. VSF could also be used to trigger an alarm or alert when motion is detected. Depending on the configuration, an alarm is triggered manually or automatically, with sensitivity and other settings that are adjusted to meet specific needs.
+
+The audio sensor function (ASF) captures the audio signal from real-world scenarios and processes the signal in raw format. The ASF could be an audio sound transducer, a microphone, microphone systems, or other audio recording devices that detect sound and capture it as audio files. This module is used to detect sound from people or objects without detecting the identity of the people, alerting a user of potential security risks or allowing them to capture recordings of an event. ASF could also trigger an alarm or alert when sound is detected. Depending on the configuration, an alarm is triggered manually or automatically, with sensitivity and other settings that are adjusted to meet specific needs.
+
+The data preprocessing function (DPPF) is responsible for transforming the captured video/audio data to a format that is suitable for subsequent processing required by users. This function supports multiple pre-processing methods, such as down/up-sampling, filtering, denoising, demosaicing, cropping, and format transformation. DPPF prepares data for analysis by cleaning, transforming, and organizing, and comprises auto functions that help deliver an enhanced signal.
+
+The feature extraction function (FXF) is used to extract the relevant and informative features from preprocessed data. However the extracted features may be high dimensional and computationally expensive. Therefore, it can be beneficial to apply a feature compression function to reduce the number of features while maintaining as much information as possible.
+
+The feature compression function (FCF) is used to reduce the data volume of the features by selecting a subset of the informative features, combining or transforming them, or using other techniques to reduce the redundancy in features. It improves the efficiency and performance of the system while maintaining the accuracy and quality of the results. FCF is a process of reducing the size of the extracted features while preserving the same level of accuracy or performance, making it more efficient for storage and analysis. There are a variety of methods for performing feature compression, including principal component analysis, singular value decomposition, and linear discriminant analysis.
+
+The feature encoding function (FEF) consists of feature conversion and a video encoder. It encodes the extracted features into compact binary bitstreams then compresses the feature using a video codec. The feature conversion module transforms data into a format that a traditional video codec can process. When the input is video, the FEF is equal to the video encoder. It is designed to be compatible with the video coding system.
+
+### 8.2 Data processing function set
+
+The data domain provides the ability to process, store, and prepare data for applications or services.
+
+The feature decoding function (FDF) corresponds to the feature compression function (FCF) in the front-end function set and is responsible for decoding/decompressing bitstreams to reconstructed features. These reconstructed features are then prepared and sent to the application or service to perform machine tasks. FDF is the process of converting encoded data back into its original form. This is typically done after the data has been encoded or transformed, such as with feature encoding, feature conversion. FDF restores the original format of the data, which is used for further analysis or display.
+
+The data storage function (DSF) has two responsibilities: managing and storing the compressed bitstream of features in a well-managed file format, which enables random access, fast search, and reorganization of the compressed feature data, and storing the reconstructed features in their original formats suitable for implementing machine tasks. DSF is used to store data in a structured format. This includes storing data in a database or other data storage system. DSF helps to ensure that data is organized and protected, making it easier to access and analyse. DSF is also used to store data in multiple formats, such as text, images, and videos, allowing for more efficient analysis and management.
+
+Lastly, the data preparation function (DPF) prepares the reconstructed feature data for transport to the application domain or service domain. DPF is used to clean, organize, and transform data before it is used for analysis. This module involves cleaning the data of errors or outliers, and transforming and organizing it in a way suitable for analysis. DPF is also used to combine data from different sources to create a dataset. After the data has been prepared, it is used for further analysis and to create predictive models.
+
+### 8.3 Algorithm function set
+
+An algorithm function set is a group of computer algorithms used to process and interpret data. These algorithms are used to create, predict, recognize, analyse or understand the content. Algorithm function sets include algorithms for video, image, audio, natural language processing, and data mining. The algorithms used in a function set will depend on the type of data being processed and the applications.
+
+The intelligent video algorithm function (IVAF) comprises a set of algorithms targeting processing of video data and features extracted from video data. IVAF is a type of computer algorithm used to process and interpret video data. This algorithm is used to detect motion, analyse actions, or recognize objects in a video. The algorithm is also used to create predictive models, such as predicting the outcome of a video or the likelihood of a certain event.
+
+The intelligent audio algorithm function (IAAF) provides algorithms focusing on audio data and features extracted from audio data. IAAF is a type of computer algorithm used to process and interpret audio data. This algorithm is used to detect sound, analyse speech, or recognize words in a recording. The algorithm is also used to create predictive models, such as predicting the outcome of a recording or the likelihood of a certain event.
+
+Natural language processing (NLP) is a field of artificial intelligence (AI) that focuses on enabling machines to understand, interpret, and respond to natural language, such as written or spoken language used by humans in everyday communication. In feature-based intelligent systems, NLP plays a role in identifying relevant features in natural language and using them to make intelligent guesses or decisions. For instance, NLP can help in sentiment analysis where it identifies the emotions that are expressed in a text to determine whether it is positive or negative.
+
+### 8.4 Service control function set
+
+The service control function set provides abilities for users to control the service of the FDIS, including activating services, deactivating services, requesting service access and managing service resources.
+
+A service control function set in FDIS is a set of functions including access registration, access authentication, identification, authorization, location, presence, data flow control and clock synchronization.
+
+### 8.5 Operation function set
+
+The operation function set provides the ability to manage and monitor the operation status of the system, including service performance, resource usage, and operation log, etc.
+
+**Feature selection:** The feature selection module has capabilities including feature categorization management, pre-processing selection, compression selection, feature extraction selection, analysis algorithm selection. It supports users choosing different data pre-processing algorithms, such as down/up-sampling, filtering, denoising, cropping, and different features, defined in [ITU-T F.748.11], to be extracted as well as related feature extraction algorithms, compression algorithms and analysis algorithms.
+
+**Data transformation:** The data transformation module has capabilities including feature format transformation. It supports transforming of different features, defined in [ITU-T F.748.11], to be stored and transmitted for analysis and display.
+
+**Data aggregation:** The data aggregation module has capabilities including feature concatenation, feature layering, feature splitting. It supports concatenate, layer and split features according to the configuration of feature selection, and thus applies to different feature decoding and analysis algorithms.
+
+### 8.6 Management function set
+
+The management function set provides the ability to manage different parts of the feature-based distributed intelligent system, including managing device configurations and resources. It also provides the capability for users to control or customize the system components in order to optimize the system performance or to meet specific requirements. The management functions in FDIS include:
+
+- User management
+- Resource management
+- System monitoring: system configuration, system deployment, system optimization
+- System log.
+
+### 8.7 Security function set
+
+The security function set provides capabilities for system security, such as encryption, data protection, access control, intrusion detection and response. It also provides capabilities to detect malicious behaviours and protect data stored within the system. The security functions in FDIS include:
+
+- Data encryption
+- Data authentication
+- Data access control
+- Data integrity checks
+- Network security
+
+- Security monitoring
+- Data masking
+- Data security auditing.
+
+### **8.8 Development function set**
+
+The development function set involves the process of building a model that can predict outputs based on inputs. This process involves using a training dataset to train the model, which involves adjusting the model's parameters based on the data to improve its accuracy. The model is tested on a separate testing dataset to evaluate how well it performs on new, unseen data. The results of the testing are used to refine the model and improve its accuracy.
+
+Some development functions in a feature-based distributed intelligent system are recommended to include:
+
+- Model training
+- Model validation
+- Model compression
+- Model visualization.
+
+### **8.9 Applications**
+
+The applications implement machine tasks from the feature data. FDIS are employed across various industries and domains to perform complex tasks that require advanced computational capabilities and decision-making skills. Some application functions in a feature-based distributed intelligent system are recommended to include:
+
+**Intelligent traffic:** FDIS can be used to extract features from traffic data such as vehicle speed, density, and volume, and use machine learning algorithms to optimize traffic flow, detect accidents or road closures, and improve safety. Applications of intelligent traffic include traffic management, urban planning, and logistics.
+
+**Smart manufacturing:** FDIS can be used to extract features from manufacturing data such as machine performance, energy usage, and product quality, and use machine learning algorithms to optimize production processes, monitor equipment health, and predict equipment failures. Applications of smart manufacturing include predictive maintenance, quality control, and supply chain optimization.
+
+**Smart city:** FDIS can be applied to analyse and process large amounts of data from various sources to optimize urban infrastructure and improve quality of life. FDIS can be used to extract features from data such as traffic, air quality, and energy consumption, and adopt machine learning algorithms to optimize transportation systems, reduce energy use, and improve public safety. Applications of smart city include traffic management, waste management, energy efficiency, and urban planning. FDIS can help city planners making decisions about infrastructure improvements, reducing energy consumption and greenhouse gas emissions, and improving the quality of life for residents.
+
+**Smart agriculture:** FDIS can be applied to extract features from agricultural data such as soil moisture, temperature, and nutrient levels, and use machine learning algorithms to optimize crop yields, monitor plant health and predict crop diseases. Applications of smart agriculture include precision farming, crop management, and resource conservation. The use of feature-based intelligent systems in agriculture can help farmers make informed decisions about planting, fertilizing, watering and harvesting their crops, leading to increased productivity, cost savings and environmental sustainability.
+
+## **9 Reference points**
+
+### **9.1 Reference point A1**
+
+Reference point A1 lies between the front-end function set and the data processing function set.
+
+It is used to deliver a compressed feature stream from the front-end function set to the data processing function set for data processing and storage.
+
+### **9.2 Reference point A2**
+
+Reference point A2 lies between the data processing function set and the algorithm function set.
+
+It is used to deliver the pre-processed feature stream from data processing function set to the algorithm function set for intelligent analysis.
+
+### **9.3 Reference point A3**
+
+Reference point A3 lies between the algorithm function set and the service control function set.
+
+It is used by the service control function set to monitoring of the status of the algorithm function set, managing and configuring services within the system, enabling the algorithm function set to adjust its algorithms. Appropriate application programming interfaces (APIs) may be used to pass the parameters and configurations into algorithms, and receive the results from the algorithm function set.
+
+### **9.4 Reference point A4**
+
+Reference point A4 lies between the applications and the service control function set.
+
+It is used by the service control function set for providing specific services or applications to end-users through the applications. It is used by the applications to provide service delivery and quality to the service control function set.
+
+### **9.5 Reference point A5**
+
+Reference point A5 lies between the service control function set and the security function set.
+
+It is used by the service control function set for managing and enforcing service-related policies. It is used by the security function set for identifying and preventing security threats.
+
+### **9.6 Reference point A6**
+
+Reference point A6 lies between the service control function set and the operation function set.
+
+It is used by the operation function set for maintaining and diagnosing network components, management of network resources, and providing feedback to the service control function set regarding potential issues or performance degradation of the service control function set.
+
+### **9.7 Reference point A7**
+
+Reference point A7 lies between the service control function set and the management function set.
+
+It is used by the management function set for overseeing, directing the operation of the network, ensuring high-level network governance and effective service delivery, and for providing feedback to the service control function set. It is used by the service control function set to provide information to the management function set regarding current service policies or the status of network resources.
+
+### **9.8 Reference point A8**
+
+Reference point A8 lies between the service control function set and the front-end function set.
+
+It is used by the service control function set to control the access authentication, and authorization of the front-end function set, and to indicate the required types of features.
+
+### **9.9 Reference point A9**
+
+Reference point A9 lies between the algorithm function set and the development function set.
+
+It is used by the development function set to send the optimized model and updated hyper parameter to the algorithm function set.
+
+## Bibliography
+
+- [b-ITU-T F.700] Recommendation ITU-T F.700 (2000), *Framework Recommendation for multimedia services.*
+- [b-ITU-T F.743] Recommendation ITU-T F.743 (V2) (2019), *Requirements and service description for video surveillance.*
+- [b-ITU-T K.142] Recommendation ITU-T K.142 (2019), *Lightning protection and earthing of video surveillance systems.*
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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@@ -0,0 +1,757 @@
+
+
+Recommendation
+
+**ITU-T F.748.25 (09/2023)**
+
+SERIES F: Non-telephone telecommunication services
+
+Multimedia services
+
+---
+
+**Requirements for speech interaction of  
+intelligent customer services**
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white grid lines and the letters 'ITU' in a bold, blue, sans-serif font.
+
+ITU logo
+
+# ITU-T F-SERIES RECOMMENDATIONS **Non-telephone telecommunication services**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| TELEGRAPH SERVICE                                               | F.1-F.109          |
+| Operating methods for the international public telegram service | F.1-F.19           |
+| The gentex network                                              | F.20-F.29          |
+| Message switching                                               | F.30-F.39          |
+| The international telemessage service                           | F.40-F.58          |
+| The international telex service                                 | F.59-F.89          |
+| Statistics and publications on international telegraph services | F.90-F.99          |
+| Scheduled and leased communication services                     | F.100-F.104        |
+| Phototelegraph service                                          | F.105-F.109        |
+| MOBILE SERVICE                                                  | F.110-F.159        |
+| Mobile services and multdestination satellite services          | F.110-F.159        |
+| TELEMATIC SERVICES                                              | F.160-F.399        |
+| Public facsimile service                                        | F.160-F.199        |
+| Teletex service                                                 | F.200-F.299        |
+| Videotex service                                                | F.300-F.349        |
+| General provisions for telematic services                       | F.350-F.399        |
+| MESSAGE HANDLING SERVICES                                       | F.400-F.499        |
+| DIRECTORY SERVICES                                              | F.500-F.549        |
+| DOCUMENT COMMUNICATION                                          | F.550-F.599        |
+| Document communication                                          | F.550-F.579        |
+| Programming communication interfaces                            | F.580-F.599        |
+| DATA TRANSMISSION SERVICES                                      | F.600-F.699        |
+| <b>MULTIMEDIA SERVICES</b>                                      | <b>F.700-F.799</b> |
+| ISDN SERVICES                                                   | F.800-F.849        |
+| UNIVERSAL PERSONAL TELECOMMUNICATION                            | F.850-F.899        |
+| ACCESSIBILITY AND HUMAN FACTORS                                 | F.900-F.999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T F.748.25
+
+# Requirements for speech interaction of intelligent customer services
+
+## Summary
+
+Recommendation ITU-T F.748.25 describes scenarios, high-level architecture, functional requirements, and performance requirements for speech interaction of intelligent customer services. Some detailed use cases and reference process for the creation of the knowledge base are described in Appendices I and II, respectively.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T F.748.25 | 2023-09-13 | 16          | 11.1002/1000/15622 |
+
+## Keywords
+
+Artificial intelligence, customer service, requirements, speech interaction, use cases.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                           | Page |
+|---------------------------------------------------------------------------|------|
+| 1 Scope .....                                                             | 1    |
+| 2 References.....                                                         | 1    |
+| 3 Definitions .....                                                       | 1    |
+| 3.1 Terms defined elsewhere .....                                         | 1    |
+| 3.2 Terms defined in this Recommendation.....                             | 2    |
+| 4 Abbreviations and acronyms .....                                        | 2    |
+| 5 Conventions .....                                                       | 2    |
+| 6 Overview .....                                                          | 3    |
+| 7 High-level architecture .....                                           | 4    |
+| 8 Requirements .....                                                      | 5    |
+| 8.1 Functional requirements .....                                         | 5    |
+| 8.2 Non-functional requirements.....                                      | 6    |
+| Appendix I Use cases of intelligent customer services.....                | 8    |
+| Appendix II Reference process for the creation of the knowledge base..... | 15   |
+| II.1 Overview .....                                                       | 15   |
+| II.2 Single domain KB establishment .....                                 | 15   |
+| II.3 Cross-domain KB establishment.....                                   | 16   |
+| Bibliography.....                                                         | 17   |
+
+
+
+# Recommendation ITU-T F.748.25
+
+## Requirements for speech interaction of intelligent customer services
+
+## 1 Scope
+
+This Recommendation specifies high-level architecture and requirements for speech interaction of intelligent customer services.
+
+This Recommendation covers the following:
+
+- High-level architecture of speech interaction of intelligent customer service;
+- Functional requirements for speech interaction of intelligent customer service;
+- Performance requirements for speech interaction of intelligent customer service.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 application** [b-ITU-T Y.2091]: A structured set of capabilities, which provide value-added functionality supported by one or more services, which may be supported by an API interface.
+
+**3.1.2 artificial intelligence (AI)** [b-ITU-T F.749.13]: An interdisciplinary field, usually regarded as a branch of computer science, dealing with models and systems for the performance of functions generally associated with human intelligence, such as reasoning and learning.
+
+**3.1.3 automatic speech recognition (ASR)** [b-ITU-T H.625]: A system that can recognize continuous speech, often having phoneme-sized references, using lexical, syntactic, semantic, and pragmatic knowledge, and reacts appropriately (therefore having interpreted the message and found the corresponding action to be taken).
+
+**3.1.4 knowledge base** [b-ITU-T F.746.3]: A collection of knowledge resources that consist of structured and unstructured data. The knowledge base is used to provide information to the various applications that are related to information provision such as the QA system and search system.
+
+**3.1.5 knowledge graph** [b-IEEE 2807]: Assemblies of knowledge elements and their relations described in a structured form.
+
+**3.1.6 mean opinion score (MOS)** [b-ITU-T P.800]: The mean of opinion scores, i.e., of the values on a predefined scale that subjects assign to their opinion of the performance of the telephone transmission system used either for conversation or for listening to spoken material.
+
+**3.1.7 natural language processing (NLP)** [b-ITU-T F.746.3]: A method that analyses text in natural languages through several processes such as part-of-speech recognition, syntactic analysis, and semantic analysis.
+
+**3.1.8 text-to-speech synthesis (TTS)** [b-ITU-T P.10/G.100-Amendment 1]: A TTS process generates a speech signal from text codes. It is usually composed of two parts:
+
+- a language-dependent text processing part (the high-level processing part), which generates from the character string (by reading rules, vocabulary and semantic analysis) a set of phonetic, prosodic, etc., parameters that are used by:
+- an acoustical signal generating part, the synthesizer itself, which generates the audible speech.
+
+**3.1.9 voice recognition** [b-ISO 9241-154]: Capability of a system to identify a specific person's voice.
+
+### **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+**3.2.1 intelligent customer service:** Customer service with intelligent capabilities, which is composed of some or all of the artificial intelligence technology capabilities such as speech recognition, natural language processing, intelligent search, and text-to-speech synthesis.
+
+**3.2.2 multi-factor authentication:** Authentication using two or more factors to achieve authentication.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                                  |
+|-----|----------------------------------|
+| AI  | Artificial Intelligence          |
+| ASR | Automatic Speech Recognition     |
+| CRM | Customer Relationship Management |
+| IVR | Interactive Voice Response       |
+| KB  | Knowledge Base                   |
+| KG  | Knowledge Graph                  |
+| MOS | Mean Opinion Score               |
+| NLP | Natural Language Processing      |
+| TTS | Text-to-Speech                   |
+
+## **5 Conventions**
+
+In this Recommendation:
+
+The keywords "be required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network
+
+operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+## 6 Overview
+
+Intelligent customer service is based on big data and artificial intelligence (AI) technologies such as natural language processing (NLP), machine learning, and large-scale knowledge management. It enables communication between enterprises and users, thereby improving operational efficiency and reducing costs.
+
+Figure 1 shows the speech interaction scenarios of intelligent customer service. These include four major scenarios.
+
+### - Voice navigation scenario
+
+Voice navigation scenario mainly describes the scenarios in which the user speaks the required service through the communication terminal, and the intelligent customer service system interacts with the customer and can quickly and accurately find relevant content for the user and make a voice reply. If the user needs to know more information, the intelligent customer service system can directly transfer the voice stream to the seat, which can provide more detailed services.
+
+### - Intelligent outbound scenario
+
+The intelligent outbound scenario mainly describes the scenarios that communicate with customers according to the preset outbound logic. Through multiple rounds of conversation and vocabulary guidance, it can complete the business function of outbound calls.
+
+### - Operator assistant scenario
+
+Operator assistant scenario mainly describes the scenarios which can obtain customer information through customer relationship management (CRM) and gives prompts to operators on the computer screen in real time to help operators communicate with the customers.
+
+### - Service quality inspection scenario
+
+The service quality inspection scenario mainly describes which system performs online analysis of the voice stream obtained by the call centre in real time through the communication network, or which system downloads the customer service audio recording file for offline analysis and processing to generate the corresponding quality inspection analysis results.
+
+![Diagram illustrating speech interaction scenarios in intelligent customer services. The diagram shows a flow from Customers (represented by icons of people, a smartphone, a telephone, and a computer monitor) to a Call centre, then to an Intelligent customer service system, which is connected to a CRM KB/KG. The Intelligent customer service system is also connected to a Seat (represented by an icon of a person wearing a headset). The Seat is connected to four scenarios: Voice navigation, Intelligent outbound, Operator assistance, and Service quality inspection. The diagram is labeled F.748.25(23).](2ba086df3506f81bae3a9b53725dcfea_img.jpg)
+
+```
+graph TD; Customers[Customers: People, Smartphone, Telephone, Computer] <--> CallCentre[Call centre]; CallCentre <--> IntelligentSystem[Intelligent customer service system]; IntelligentSystem --- CRM[CRM KB/KG]; IntelligentSystem <--> Seat[Seat: Person with Headset]; Seat <--> VoiceNavigation[Voice navigation]; Seat <--> IntelligentOutbound[Intelligent outbound]; Seat <--> OperatorAssistance[Operator assistance]; Seat <--> ServiceQualityInspection[Service quality inspection];
+```
+
+F.748.25(23)
+
+Diagram illustrating speech interaction scenarios in intelligent customer services. The diagram shows a flow from Customers (represented by icons of people, a smartphone, a telephone, and a computer monitor) to a Call centre, then to an Intelligent customer service system, which is connected to a CRM KB/KG. The Intelligent customer service system is also connected to a Seat (represented by an icon of a person wearing a headset). The Seat is connected to four scenarios: Voice navigation, Intelligent outbound, Operator assistance, and Service quality inspection. The diagram is labeled F.748.25(23).
+
+**Figure 1 – Speech interaction scenarios in intelligent customer services**
+
+## 7 High-level architecture
+
+Figure 2 presents the high-level architecture for speech interaction of intelligent customer services according to the use cases.
+
+![Figure 2: High-level architecture for speech interaction of intelligent customer services. The diagram shows a three-layer structure: Applications layer, Services layer, and Network layer, all contained within an 'Intelligent customer service' box. The Applications layer includes Voice navigation, Intelligence outbound, Operator assistance, and Service quality inspection. The Services layer includes Natural language processing, Automatic speech recognition, Text to speech, and KB/KG. The Network layer includes Voice exchange. All three layers are connected to a 'Call centre' box at the bottom via double-headed arrows.](cfda9df1319e04207eb28bcefd1dab7b_img.jpg)
+
+```
+graph TD
+    subgraph ICS [Intelligent customer service]
+        subgraph AL [Applications layer]
+            V[Voice navigation]
+            IO[Intelligence outbound]
+            OA[Operator assistance]
+            SQI[Service quality inspection]
+        end
+        subgraph SL [Services layer]
+            NLP[Natural language processing]
+            ASR[Automatic speech recognition]
+            TTS[Text to speech]
+            KBKG[KB/KG]
+        end
+        subgraph NL [Network layer]
+            VE[Voice exchange]
+        end
+        AL <--> SL
+        SL <--> NL
+    end
+    NL <--> CC[Call centre]
+```
+
+Figure 2: High-level architecture for speech interaction of intelligent customer services. The diagram shows a three-layer structure: Applications layer, Services layer, and Network layer, all contained within an 'Intelligent customer service' box. The Applications layer includes Voice navigation, Intelligence outbound, Operator assistance, and Service quality inspection. The Services layer includes Natural language processing, Automatic speech recognition, Text to speech, and KB/KG. The Network layer includes Voice exchange. All three layers are connected to a 'Call centre' box at the bottom via double-headed arrows.
+
+F.748.25(23)
+
+**Figure 2 – High-level architecture for speech interaction of intelligent customer services**
+
+The high-level architecture for speech interaction of intelligent customer services covers three layers: applications, services and networks. A general description of these three blocks is presented below.
+
+- **Applications layer:** Applications layer is the software for realizing the speech interaction of intelligent customer service. The applications include voice navigation, intelligence outbound, operator assistance and service quality inspection, etc.
+
+A detailed description of the applications can be found in Appendix I.
+
+- **Services layer:** Services layer is the basic AI functional modules for supporting applications. The services include natural language processing (NLP), automatic speech recognition (ASR), text-to-speech synthesis (TTS), and knowledge base (KB)/knowledge graph (KG).
+
+The NLP function uses algorithms to understand and manipulate human language. The NLP function can realize applications of intelligent customer service through algorithms such as intention understanding, named entity recognition, text classification, etc.
+
+The ASR function uses algorithms to convert human speech into text. The ASR function can realize multiple applications in intelligent customer service through single-sentence speech recognition, continuous speech recognition, etc.
+
+The TTS function uses algorithms to synthesize natural-sounding speech in multiple languages. This function can be used in user interaction applications of intelligent customer service.
+
+The KB/KG contains information about words, sentences, and the relationship between knowledge. It describes all the knowledge information and the relationship between each piece of knowledge information used in the intelligent customer service.
+
+- **Network layer:** Network layer is the communication network's capability for voice exchange between the call centre and services layer. The voice exchange supports multimedia voice, voice call in and call out, voice transfer and voice recording functions, etc.
+
+## 8 Requirements
+
+### 8.1 Functional requirements
+
+The functional requirements for intelligent customer service are as follows:
+
+- The speech interaction of intelligent customer service is required to have the ability to recognize keywords in sentences;
+- The speech interaction of intelligent customer service is required to support speech interaction with multiple access channels, and supports one or more speech interaction methods such as fixed telephone network, mobile telephone network, Internet, and other access methods;
+- The presentation of the speech interaction results of the intelligent customer service is required to include the results of TTS, and can optionally include the presentation of information such as text and graphics;
+- The speech interaction of intelligent customer service is recommended to support automatic identification of voice start point and end point;
+- The speech interaction of intelligent customer service can optionally support the dynamically generate guidance and prompt words based on the results of ASR and NLP;
+- The speech interaction of intelligent customer service can optionally support the service quality inspection of operators based on the results of ASR and NLP;
+- The ASR function is recommended to have the ability to recognize continuous speech;
+- The ASR function is recommended to support the language recognition function, that is, to determine the language of the voice based on the user's voice input;
+- The ASR function is recommended to support mixed language recognition, that is, support the recognition of different language words in sentences;
+- The NLP function of intelligent customer service is recommended to support the understanding of abbreviations, aliases, locations and numbers;
+- The NLP function of intelligent customer service is recommended to support the fault-tolerant understanding of typical misleading words;
+- The NLP function of intelligent customer service is recommended to support multiple rounds of dialogue;
+- The NLP function of intelligent customer service can optionally support the understanding of subordinate relationships, the understanding of partial-overall relationships, the understanding of geographic relationships, the understanding of causality, the understanding of sequential relationships, and the understanding of proximal relationships;
+- The TTS function of intelligent customer service is required to support multi-language synthesis and multi-timbre synthesis such as young female voices and young male voices;
+- The TTS function of intelligent customer service can optionally support mixed language and personalized TTS;
+- The purpose of building a KB of intelligent customer service is mainly to organize and manage knowledge according to the business requirements, including keyword libraries, service processes, question templates, or KGs constructed in the form of triples.
+  - a) The KB of intelligent customer service is required to have the function of keyword identification and maintenance according to the business requirements and support the addition, deletion, and modification of characteristic keywords of customer service system services.
+  - b) The KB of intelligent customer service is required to have the maintenance function of static prompts, that is, the guiding prompt function according to the business
+
+requirements, and support the addition, deletion, and modification of static prompting functions of the customer service system services.
+
+- c) The KB of intelligent customer service is required to have the service process maintenance function according to the business requirements, and support the addition, deletion, and modification of the service process of the customer service system.
+- d) The KB of intelligent customer service is required to have the function of editing question templates according to the business requirements, and support the addition, deletion, and modification of semantic expressions of customer service questions.
+- e) The KB of intelligent customer service can optionally support the knowledge construction based on the KG technology in the form of ontology/triple.
+
+– The speech interaction of intelligent customer service that will use voice recognition for authentication, or verification for any use case, especially for critical transactions like services provisioning, financial transactions, or dealing with personal or financial data, is required to consider the implementation of multi-factor authentication beyond voice recognition. This is to protect customers' sensitive information and accounts from voice cloning trials by fraudsters by creating synthetic audio recordings of a person's voice that are often indistinguishable from authentic voices;
+
+– The speech interaction of intelligent customer service is recommended to have the below measures to detect and prevent fraudulent activities such as suspicious account activity, unusual recognition attempts, or transaction patterns during the user verification process:
+
+- a) The system can optionally monitor transactions in real-time to detect any suspicious activity. While machine learning algorithms can optionally be used to analyse patterns of fraudulent behaviour and identify potential fraudsters.
+- b) The system can optionally send alerts to designated personnel when it detects suspicious activity.
+- c) The system can optionally block transactions that have a high-risk score to prevent fraud.
+- d) The system can optionally analyse user behaviour to detect any anomalies or suspicious activity.
+
+### 8.2 Non-functional requirements
+
+#### 8.2.1 Performance requirements
+
+##### 8.2.1.1 Response time of speech interaction
+
+The response time of speech interaction refers to the time between the end of the user input and the return of the result.
+
+The interactive response time calculation method is shown in the formula.
+
+$$T_{ack} = t_r - t_e$$
+
+$T_{ack}$  – Response time
+
+$t_r$  – Result output moment
+
+$t_e$  – Voice input end time
+
+If the speech interaction system supports the recognition result to be returned multiple times,  $t_r$  should be the time when the first part of the recognition result is returned.
+
+In the case of multiple rounds of speech interaction process,  $T_{ack}$  refers to the response time of each round of speech interaction.
+
+In order to ensure the service quality of intelligent customer service,  $T_{ack}$  is recommended to be less than an appropriate threshold.
+
+##### 8.2.1.2 Speech interaction success rate
+
+In the interaction process of the speech interaction system, the user can obtain the result within the predetermined interaction rounds, and it can then be judged that the current rounds of interaction are successful; otherwise, it is judged that these rounds of interaction have failed.
+
+The calculation method of the interaction success rate is as follows:
+
+$$P_s = \frac{S}{S + F} \times 100\%$$
+
+$P_s$  – Interaction success rate
+
+$S$  – The number of successful interactions
+
+$F$  – The number of failed interactions
+
+In order to ensure the service quality of intelligent customer service,  $P_s$  is recommended to be higher than an appropriate threshold.
+
+##### 8.2.1.3 ASR accuracy index
+
+In the speech interaction system, it is recommended that the word accuracy of keyword speech recognition should be calculated in different noise environments (e.g., noise intensity below 50 dB and noise intensity of 60 dB to 65 dB, etc.).
+
+In the speech interaction system, it is recommended that the word accuracy rate of continuous speech recognition should be calculated in, in different noise environments (e.g., noise intensity below 50 dB and noise intensity of 60 dB to 65 dB, etc.).
+
+In order to ensure the service quality of intelligent customer service, it is recommended that the ASR accuracy should be higher than an appropriate threshold.
+
+##### 8.2.1.4 TTS evaluation
+
+TTS test adopts the mean opinion score (MOS) test method for evaluation. Through the result of the intelligent customer service speech synthesis, it tests the difference in sound quality, intelligibility and naturalness between the synthesized speech and the human speech, numerically quantifies the test result with the average MOS score, and then records the average result.
+
+In order to ensure the service quality of intelligent customer service, MOS is recommended to be greater than or equal to an appropriate threshold.
+
+##### 8.2.1.5 NLP accuracy index
+
+The NLP ability is recommended to be tested by various people with multiple rounds. The calculation method for the correct rate of NLP is as follows.
+
+$$R_{ss} = \frac{N_{ss}}{N} \times 100\%$$
+
+$R_{ss}$  – NLP rate
+
+$N_{ss}$  – The number of times the intention and semantic elements are correctly judged
+
+$N$  – The total number of correct texts
+
+In order to ensure the service quality of intelligent customer service,  $R_{ss}$  is recommended to be higher than an appropriate threshold.
+
+## Appendix I
+
+### Use cases of intelligent customer services
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### I.1 Use cases
+
+#### I.1.1 Use cases for full speech interaction of intelligent customer services
+
+The full speech interaction use case means that all the functions are completed by the speech interaction system, and there is no operator participation during the interaction. It may include:
+
+- a) The call centre recognizes the customer's voice input through ASR and NLP technology, then automatically responds to the customer through TTS technology.
+
+![Diagram of full speech interaction of intelligent customer service (Model A)](16c1175b5f05a4b55e6d396fc51b15b3_img.jpg)
+
+The diagram illustrates the workflow of a full speech interaction system. At the top, three icons represent customer input: a smartphone, a fixed telephone, and a computer monitor. Arrows from these icons point to a box containing 'Automatic call distributor' and 'Multimedia gateway'. From this box, an arrow labeled '2' points down to a central box containing 'Computer telephony integrator' and 'IVR'. To the left of this central box is an 'ASR' (Automatic Speech Recognition) block, and to the right is a 'TTS' (Text-to-Speech) block. Below the central box is an 'NLP' (Natural Language Processing) block. Arrows indicate the flow of information: '3' from IVR to ASR, '4' from ASR to Computer telephony integrator, '5' from Computer telephony integrator to NLP, '6' from NLP to IVR, '7' from IVR to TTS, and '8' from TTS to IVR. Finally, an arrow labeled '9' points from the IVR back up to the 'Automatic call distributor / Multimedia gateway' box, and an arrow labeled '10' points from that box to the output icons (smartphone, telephone, computer monitor). A small label 'F.748.25(23)' is in the bottom right corner of the diagram area.
+
+Diagram of full speech interaction of intelligent customer service (Model A)
+
+**Figure I.1 – Example of full speech interaction of intelligent customer service (Model A)**
+
+The description of the workflow is as below:
+
+- 1) The customer calls the call centre using a cell phone, fixed telephone or a computer and speaks according to voice prompts;
+- 2) The automatic call distributor / multimedia gateway of the call centre transfers the speech to the computer telephony integrator / interactive voice response (IVR);
+- 3) IVR transfers the call to the ASR function;
+- 4) The ASR function converts the speech to text and returns the result to the IVR;
+- 5) IVR uses NLP technology to recognize user intent for the text;
+- 6) NLP function returns the result to the IVR;
+- 7) IVR matches the predefined process based on the results of NLP to synthesize the next speech;
+- 8) TTS function returns the speech to the IVR;
+- 9) IVR transfers the speech to the automatic call distributor / multimedia gateway through the call connection;
+
+- 10) The automatic call distributor / multimedia gateway transfers the speech to the customer. Then the customer starts the next round of dialogue.
+- b) Instead of traditional manual telephone return visits and telephone notifications, the standard services of the call centre can be implemented through a dialogue between the robot and the user.
+
+![Diagram of full speech interaction of intelligent customer service (Model B)](bd0b93e7a46ede276d0a3b79ac487bd9_img.jpg)
+
+The diagram illustrates the workflow of an intelligent customer service system (Model B). At the top, three icons represent the customer: a smartphone, a telephone, and a computer monitor. Arrows labeled 5 and 6 point from these icons to a central box containing 'Automatic call distributor' and 'Multimedia gateway'. From this box, an arrow labeled 7 points down to a 'Computer telephony integrator / IVR' box. To the left of the IVR is an 'ASR' (Automatic Speech Recognition) box, connected by arrows 8 and 9. To the right is a 'TTS' (Text-to-Speech) box, connected by arrows 2, 3, and 12. Below the IVR are two boxes: 'NLP' (Natural Language Processing) and 'Service template', connected by arrows 10, 11, and 1 respectively. A small label 'F.748.25(23)' is in the bottom right corner.
+
+Diagram of full speech interaction of intelligent customer service (Model B)
+
+**Figure I.2 – Example of full speech interaction of intelligent customer service (Model B)**
+
+The description of the workflow is as below:
+
+- 1) The service template is pre-installed in the IVR;
+- 2) The call centre initiates a call connection and the IVR requests the TTS function for the service template;
+- 3) The TTS function returns the speech to the IVR;
+- 4) IVR transfers the speech to the automatic call distributor / multimedia gateway through the call connection;
+- 5) The automatic call distributor / multimedia gateway transfers the speech to the customer;
+- 6) The customer answers the call and speaks according to voice prompts;
+- 7) The automatic call distributor / multimedia gateway of the call centre transfers the speech to the computer telephony integrator / IVR;
+- 8) IVR transfers the call to the ASR function;
+- 9) The ASR function converts the speech to text and returns the result to the IVR;
+- 10) IVR uses NLP technology to recognize user intent for the text;
+- 11) NLP function returns the result to IVR;
+- 12) IVR matches the predefined template based on the results of the NLP to the next round of dialogue.
+
+#### I.1.2 Use cases for partial speech interaction of intelligent customer services
+
+Partial speech interaction use cases refers to the participation of the operator throughout the speech interaction process. It may include:
+
+- a) During the speech interaction process, the user cannot obtain the target result, or the target result does not conform to the service specification. The system transfers the interactive session to the operator, and the service will be provided by the operator.
+
+![Diagram illustrating the workflow of partial speech interaction of intelligent customer service (Mode A). The diagram shows a flow from a customer (represented by icons of a cell phone, fixed telephone, and computer) through an Automatic call distributor / Multimedia gateway, then to a Computer telephony integrator / IVR. The IVR interacts with ASR (Automatic Speech Recognition), NLP (Natural Language Processing), and TTS (Text-to-Speech). The IVR also connects to a Seat (operator). The flow is numbered 1 through 12, showing the sequence of interactions: 1) Customer call, 2) Call transfer to integrator, 3) IVR to ASR, 4) ASR to IVR, 5) IVR to NLP, 6) NLP to IVR, 7) IVR to Seat, 8) Seat to IVR, 9) IVR to TTS, 10) TTS to IVR, 11) IVR to gateway, 12) Gateway to customer.](5cab96b2d23174c25919840ecd50aa48_img.jpg)
+
+```
+
+graph TD
+    subgraph Customer [Customer]
+        direction TB
+        C1[Cell phone]
+        C2[Fixed telephone]
+        C3[Computer]
+    end
+    subgraph Gateway [Automatic call distributor / Multimedia gateway]
+        direction LR
+        G1[Automatic call distributor]
+        G2[Multimedia gateway]
+    end
+    subgraph Integrator [Computer telephony integrator / IVR]
+        direction LR
+        I1[Computer telephony integrator]
+        I2[IVR]
+    end
+    ASR[ASR]
+    NLP[NLP]
+    TTS[TTS]
+    Seat[Seat]
+
+    Customer -- 1 --> Gateway
+    Gateway -- 2 --> Integrator
+    Integrator -- 3 --> ASR
+    ASR -- 4 --> Integrator
+    Integrator -- 5 --> NLP
+    NLP -- 6 --> Integrator
+    Integrator -- 7 --> Seat
+    Seat -- 8 --> Integrator
+    Integrator -- 9 --> TTS
+    TTS -- 10 --> Integrator
+    Integrator -- 11 --> Gateway
+    Gateway -- 12 --> Customer
+  
+```
+
+Diagram illustrating the workflow of partial speech interaction of intelligent customer service (Mode A). The diagram shows a flow from a customer (represented by icons of a cell phone, fixed telephone, and computer) through an Automatic call distributor / Multimedia gateway, then to a Computer telephony integrator / IVR. The IVR interacts with ASR (Automatic Speech Recognition), NLP (Natural Language Processing), and TTS (Text-to-Speech). The IVR also connects to a Seat (operator). The flow is numbered 1 through 12, showing the sequence of interactions: 1) Customer call, 2) Call transfer to integrator, 3) IVR to ASR, 4) ASR to IVR, 5) IVR to NLP, 6) NLP to IVR, 7) IVR to Seat, 8) Seat to IVR, 9) IVR to TTS, 10) TTS to IVR, 11) IVR to gateway, 12) Gateway to customer.
+
+**Figure I.3 – Example of partial speech interaction of intelligent customer service (Mode A)**
+
+The description of the workflow is as below:
+
+- 1) The customer calls the call centre using a cell phone, fixed telephone or computer and speaks according to voice prompts;
+  - 2) The automatic call distributor / multimedia gateway of the call centre transfers the speech to the computer telephony integrator / IVR;
+  - 3) IVR transfers the call to the ASR function;
+  - 4) The ASR function converts the speech to text and returns the text to the IVR;
+  - 5) IVR uses NLP technology to recognize user intent for the text;
+  - 6) The NLP function returns the result to the IVR;
+  - 7) IVR cannot match the right process based on the results of NLP and transfers the call to the seat;
+  - 8) The operator communicates with the customer and helps the customer deal with problems;
+  - 9) The operator determines to return the result with the IVR and transfers the call to the IVR. IVR requests the TTS function to synthesize the speech;
+  - 10) The TTS function returns the speech to IVR;
+  - 11) IVR transfers the speech to the automatic call distributor / multimedia gateway through the call connection;
+  - 12) The automatic call distributor / multimedia gateway transfers the speech to the customer.
+- b) Speech interaction system only performs certain functions, such as IVR navigation. That is, the user speaks the specific words, and after the ASR, the speech is transferred to a specific operator for follow-up service.
+
+![Diagram illustrating the workflow of intelligent customer service (Mode B). The process starts with a customer (represented by icons of a smartphone, fixed telephone, and computer) sending input (1) to an 'Automatic call distributor / Multimedia gateway'. This unit then transfers the call (2) to a 'Computer telephony integrator / IVR'. The IVR transfers the call (3) to the 'ASR' (Automatic Speech Recognition) function, which returns the result (4) to the IVR. The IVR then transfers the call (5) to a 'Seat' (operator). The operator communicates (6) with the customer and determines the result (7). The IVR requests the 'TTS' (Text-to-Speech) function (8) to synthesize the speech, which returns the speech (9) to the IVR. Finally, the IVR transfers the call (10) back to the 'Automatic call distributor / Multimedia gateway', which then transfers the speech (10) to the customer.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+```
+
+graph TD
+    Customer[Customer: Smartphone, Phone, Computer] -- 1 --> Gateway[Automatic call distributor / Multimedia gateway]
+    Gateway -- 2 --> IVR[Computer telephony integrator / IVR]
+    IVR -- 3 --> ASR[ASR]
+    ASR -- 4 --> IVR
+    IVR -- 5 --> Seat[Seat]
+    Seat -- 6 --> IVR
+    IVR -- 7 --> TTS[TTS]
+    TTS -- 8 --> IVR
+    IVR -- 9 --> Gateway
+    Gateway -- 10 --> Customer
+  
+```
+
+Diagram illustrating the workflow of intelligent customer service (Mode B). The process starts with a customer (represented by icons of a smartphone, fixed telephone, and computer) sending input (1) to an 'Automatic call distributor / Multimedia gateway'. This unit then transfers the call (2) to a 'Computer telephony integrator / IVR'. The IVR transfers the call (3) to the 'ASR' (Automatic Speech Recognition) function, which returns the result (4) to the IVR. The IVR then transfers the call (5) to a 'Seat' (operator). The operator communicates (6) with the customer and determines the result (7). The IVR requests the 'TTS' (Text-to-Speech) function (8) to synthesize the speech, which returns the speech (9) to the IVR. Finally, the IVR transfers the call (10) back to the 'Automatic call distributor / Multimedia gateway', which then transfers the speech (10) to the customer.
+
+F.748.25(23)
+
+**Figure I.4 – Example of partial speech interaction of intelligent customer service (Mode B)**
+
+The description of the workflow is as below:
+
+- 1) The customer calls the call centre using a cell phone, fixed telephone or computer and speaks according to voice prompts;
+- 2) The automatic call distributor / multimedia gateway of the call centre transfers the speech to the computer telephony integrator / IVR;
+- 3) IVR transfers the call to the ASR function;
+- 4) The ASR function converts the speech to text and returns the result to the IVR;
+- 5) IVR matches the right process based on the results of the ASR and transfers the call to the specific seat;
+- 6) The operator communicates with the customer and helps the customer deal with the problems;
+- 7) The operator determines to return the result with IVR and transfers the call to the IVR. IVR requests the TTS function to synthesize the speech;
+- 8) TTS function returns the speech to the IVR;
+- 9) IVR transfers the speech to the automatic call distributor / multimedia gateway through the call connection;
+- 10) The automatic call distributor / multimedia gateway transfers the speech to the customer.
+
+#### I.1.3 Use cases for service quality inspection of intelligent customer services
+
+Traditional service quality inspection requires a lot of workloads. Through ASR and NLP techniques, the operator's service quality can be automatically evaluated.
+
+![Diagram illustrating the workflow for service quality inspection of intelligent customer services. The process starts with a customer (represented by icons of a cell phone, fixed telephone, and computer) making a call (1). The call is routed through an Automatic call distributor / Multimedia gateway (2) to a Computer telephony integrator / IVR (3). The operator (Seat) communicates with the customer (3). The quality inspection function (4) performs quality inspection online/offline according to the voice of the operator. The quality inspection function transfers the voice to the ASR function (5). The quality inspection module supports voice information detection such as speech speed and mute in different roles during the conversation (6). The Inspector (represented by an icon of a person with a headset) receives the output from the ASR function (6).](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+```
+
+graph TD
+    subgraph Customer_Inputs [ ]
+        direction TB
+        C1[Cell phone icon]
+        C2[Fixed telephone icon]
+        C3[Computer monitor icon]
+    end
+    C1 -- 1 --> ACD[Automatic call distributor]
+    C2 -- 1 --> MG[Multimedia gateway]
+    subgraph ACD_MG [ ]
+        direction LR
+        ACD
+        MG
+    end
+    ACD_MG -- 2 --> CTI_IVR[Computer telephony integrator]
+    subgraph CTI_IVR [ ]
+        direction LR
+        CTI
+        IVR
+    end
+    CTI_IVR -- 3 --> Seat[Seat icon]
+    CTI_IVR -- 4 --> QI[Quality inspection]
+    QI -- 5 --> ASR[ASR]
+    ASR -- 6 --> Inspector[Inspector icon]
+    style Customer_Inputs fill:none,stroke:none
+    style ACD_MG fill:none,stroke:none
+    style CTI_IVR fill:none,stroke:none
+    style Seat fill:none,stroke:none
+    style Inspector fill:none,stroke:none
+    style QI fill:none,stroke:none
+    style ASR fill:none,stroke:none
+  
+```
+
+Diagram illustrating the workflow for service quality inspection of intelligent customer services. The process starts with a customer (represented by icons of a cell phone, fixed telephone, and computer) making a call (1). The call is routed through an Automatic call distributor / Multimedia gateway (2) to a Computer telephony integrator / IVR (3). The operator (Seat) communicates with the customer (3). The quality inspection function (4) performs quality inspection online/offline according to the voice of the operator. The quality inspection function transfers the voice to the ASR function (5). The quality inspection module supports voice information detection such as speech speed and mute in different roles during the conversation (6). The Inspector (represented by an icon of a person with a headset) receives the output from the ASR function (6).
+
+**Figure I.5 – Example of service quality inspection of intelligent customer services**
+
+The description of the workflow is as below:
+
+- 1) The customer calls the call centre using a cell phone, fixed telephone or computer and speaks according to voice prompts;
+- 2) The automatic call distributor / multimedia gateway of the call centre transfers the speech to the computer telephony integrator / IVR;
+- 3) The operator communicates with the customer and helps the customer deal with the problems;
+- 4) The quality inspection function can perform quality inspection online/offline according to the voice of the operator;
+- 5) The quality inspection function transfers the voice to the ASR function;
+- 6) The quality inspection module supports voice information detection such as speech speed and mute in different roles during the conversation.
+
+#### **I.1.4 Use cases for operator assistance of intelligent customer services**
+
+The operator assistance system can identify the conversation between the operators and the customers through ASR technology during the call and capture the key information through the NLP technology. It can then obtain customer information through the CRM and give prompts to operators on the computer screen in real time (including knowledge points and verbal reminders, automated extraction of customer portraits, analysis of customer purchase intentions, etc.) to help operators communicate with the customers.
+
+![Figure I.6 – Example of operator assistance of intelligent customer services. The diagram illustrates a workflow for intelligent customer service. At the top, three icons represent customer contact methods: a smartphone, a fixed telephone, and a computer monitor. An arrow labeled '1' points from these icons to a box containing 'Automatic call distributor' and 'Multimedia gateway'. An arrow labeled '2' points from this box to another box containing 'Computer telephony integrator' and 'IVR'. An arrow labeled '3' points from the 'IVR' component to a 'Seat' icon (representing an operator). An arrow labeled '4' points from the 'Computer telephony integrator' to an 'Operator assistance system' box. From the 'Operator assistance system', an arrow labeled '5' points down to an 'ASR' box, and an arrow labeled '7' points up to an 'NLP' box. From the 'ASR' box, an arrow labeled '6' points back up to the 'Operator assistance system'. From the 'NLP' box, an arrow labeled '9' points down to the 'Operator assistance system', and an arrow labeled '8' points right to a 'Key words recognition' box. From the 'Key words recognition' box, an arrow labeled '10' points down to an oval labeled 'KB/KG'. From the 'KB/KG' oval, an arrow labeled '11' points back to the 'Operator assistance system'. Finally, an arrow points from the 'Operator assistance system' to a computer monitor icon next to the 'Seat' icon.](9c6461e1e94afae4dec455e69a2ce152_img.jpg)
+
+Figure I.6 – Example of operator assistance of intelligent customer services. The diagram illustrates a workflow for intelligent customer service. At the top, three icons represent customer contact methods: a smartphone, a fixed telephone, and a computer monitor. An arrow labeled '1' points from these icons to a box containing 'Automatic call distributor' and 'Multimedia gateway'. An arrow labeled '2' points from this box to another box containing 'Computer telephony integrator' and 'IVR'. An arrow labeled '3' points from the 'IVR' component to a 'Seat' icon (representing an operator). An arrow labeled '4' points from the 'Computer telephony integrator' to an 'Operator assistance system' box. From the 'Operator assistance system', an arrow labeled '5' points down to an 'ASR' box, and an arrow labeled '7' points up to an 'NLP' box. From the 'ASR' box, an arrow labeled '6' points back up to the 'Operator assistance system'. From the 'NLP' box, an arrow labeled '9' points down to the 'Operator assistance system', and an arrow labeled '8' points right to a 'Key words recognition' box. From the 'Key words recognition' box, an arrow labeled '10' points down to an oval labeled 'KB/KG'. From the 'KB/KG' oval, an arrow labeled '11' points back to the 'Operator assistance system'. Finally, an arrow points from the 'Operator assistance system' to a computer monitor icon next to the 'Seat' icon.
+
+F.748.25(23)
+
+**Figure I.6 – Example of operator assistance of intelligent customer services**
+
+The description of the workflow is as below:
+
+- 1) The customer calls the call centre using a cell phone, fixed telephone or computer and speaks according to voice prompts;
+- 2) The automatic call distributor / multimedia gateway of the call centre transfers the speech to the computer telephony integrator / IVR;
+- 3) The operator communicates with the customer and helps the customer deal with the problems;
+- 4) The operator assistance system can give the information to the operator according to the voice of the operator and the customer;
+- 5) The operator assistance system transfers the voice to the ASR function;
+- 6) The ASR function converts the speech to text and returns the text to the operator assistance system;
+- 7) The operator assistance system uses the NLP technology to perform NLP for the text;
+- 8) Key words recognition module performs keywords' detection;
+- 9) The NLP function returns the text and keywords result to the operator assistance system;
+- 10) The operator assistance system obtains customer information from KB/KG;
+- 11) The operator assistance system gives prompts to operators on the computer screen in real time.
+
+#### I.1.5 Use case of a phone-based voice authentication
+
+Use case of a phone-based voice authentication, as an example of using voice recognition within an intelligent customer service.
+
+The below workflow outlines a phone-based voice authentication that uses a combination of identifying information, voice input, and additional authentication factors to granting access to users' accounts or other protected resources.
+
+The description of the workflow is as below:
+
+- a) The user calls the authentication system through IVR using their registered phone number.
+
+- b) The system prompts the user to provide their username or other identifying information such as an account number or national identification number.
+- c) The user provides their username or other identifying information using a voice input.
+- d) The system verifies the user based on the provided information and prompts the user to provide a voice sample for verification.
+- e) The user provides a voice sample for verification.
+- f) If the voice sample matches, the system prompts the user to provide additional authentication factors such as password, or PIN, and a physical security token.
+- g) The user provides the additional authentication factor(s) as requested.
+- h) If all authentication factors are successfully verified, the system grants access to the user's account or other protected resource.
+
+It is worth noting that this is just one example workflow, and the actual implementation may vary depending on the specific requirements and technologies used.
+
+## Appendix II
+
+### Reference process for the creation of the knowledge base
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### II.1 Overview
+
+The construction of the KB of the intelligent customer service system starts with a single domain, and then expands to multiple domains.
+
+![Flowchart illustrating the basic process of a KB establishment. The steps are: 1. Collect and sort out the required knowledge materials in the intelligent customer service system; 2. Establish a single domain KB; 3. Cross-domain knowledge integration; 4. General KB and Cross-domain KB; 5. Intelligent customer service system KB.](a24e89a6fe9bb70c83f8bf5202baba95_img.jpg)
+
+```
+graph TD; A[Collect and sort out the required knowledge materials in the intelligent customer service system] --> B[Establish a single domain KB]; B --> C[Cross-domain knowledge integration]; C --> D[(General KB)]; C --> E[(Cross-domain KB)]; D --> F[(Intelligent customer service system KB)]; E --> F
+```
+
+Flowchart illustrating the basic process of a KB establishment. The steps are: 1. Collect and sort out the required knowledge materials in the intelligent customer service system; 2. Establish a single domain KB; 3. Cross-domain knowledge integration; 4. General KB and Cross-domain KB; 5. Intelligent customer service system KB.
+
+F.748.25(23)
+
+**Figure II.1 – Basic process of a KB establishment**
+
+Figure II.1 describes a basic process example for a knowledge base (KB) creation. First, a single-domain KB is established through natural language technologies such as entity recognition and relation extraction. Then, through knowledge mapping and fusion technologies, cross-domain knowledge integration is realized, and then the general domain KB and cross-domain KB are established.
+
+### II.2 Single domain KB establishment
+
+The intelligent customer service system has accumulated a large number of fuzzy and inaccurate knowledge in the process of use. The existence of these knowledge points is a large amount of incomplete, noisy, fuzzy, random practical application data (involving natural language technology). Therefore, the process of extracting hidden but potentially useful information and knowledge is very important and necessary, so that much historical data that could not be understood before can be used.
+
+The process of single domain knowledge mining is divided into the following steps:
+
+- Keyword libraries construction: Based on the NLP technology, discovering concepts in the domain through entity recognition and syntactic analysis technologies, mining the relationships between concepts, and automatically or semi-automatically constructing domain semantic lexicons based on semantic network technology;
+- Construction of a candidate object: Semantic understanding and induction of concepts in the semantic lexicon, and construction of a candidate object;
+- Submit for manual review: This semi-automatic knowledge mining method effectively speeds up the process of domain KB construction and reduces costs.
+
+### **II.3 Cross-domain KB establishment**
+
+Based on a KB of a single domain, knowledge of a new domain is gradually integrated. Make the KB adjust with the integration of new domain knowledge, adapt it to the requirements of the corresponding multiple domains, and finally realize the integration of a cross-domain knowledge.
+
+- Integration of words in various fields: Merge common words that overlap in the KB of various fields and classify professional words in vertical fields according to different fields.
+- Combination of object classes: To integrate knowledge of the new domain into the existing KB. Firstly, it is necessary to find similar object classes in the existing knowledge by the method of object class matching, and then merge. Object class merging is to integrate multiple object classes together, eliminate overlapping parts and remove inconsistent parts, so that the new object class is more reasonable and can better express the concept of these merged object classes.
+- Combination of knowledge: In addition to the specific professional knowledge content of each domain, there is also a part of knowledge that is common to multiple domains. The general knowledge content in various domains needs to be extracted to form a general KB.
+
+## Bibliography
+
+- [b-ITU-T F.746.3] Recommendation ITU-T F.746.3 (2015), *Intelligent question answering service framework*.
+- [b-ITU-T F.749.13] Recommendation ITU-T F.749.13 (2021), *Framework and requirements for civilian unmanned aerial vehicle flight control using artificial intelligence*.
+- [b-ITU-T H.625] Recommendation ITU-T H.625 (2017), *Architecture for network-based speech-to-speech translation services*.
+- [b-ITU-T P.10/G.100] Recommendation ITU-T P.10/G.100 (2017) – Amendment 1 (2019), *New definitions for inclusion in Recommendation ITU-T P.10/G.100. Vocabulary for performance, quality of service and quality of experience Amendment 1*.
+- [b-ITU-T P.800] Recommendation ITU-T P.800 (1996), *Methods for subjective determination of transmission quality*.
+- [b-ITU-T Y.2091] Recommendation ITU-T Y.2091 (2011), *Terms and definitions for next generation networks*.
+- [b-IEEE 2807] IEEE 2807-2022, *IEEE Standard for Framework of Knowledge Graphs*.  
+<<https://standards.ieee.org/ieee/2807/7525/>>
+- [b-ISO 9241-154] ISO 9241-154:2013, *Ergonomics of human-system interaction – Part 154: Interactive voice response (IVR) applications*.  
+<[https://www.iso.org/standard/52172.html#:~:text=ISO%209241%2D154%3A2013%20gives,ASR\)%20as%20the%20input%20mechanism.](https://www.iso.org/standard/52172.html#:~:text=ISO%209241%2D154%3A2013%20gives,ASR)%20as%20the%20input%20mechanism.)>
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                                                                                           |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| Series X        | Data networks, open system communications and security                                                                                                    |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |