ITU-T T 62-1993 Control Procedures for Teletex and Group 4 Facsimile Services - Terminal Services Terminal Equipments and Protocols for Telematic Services (Study Group VIII 168 pp).pdf

1、 STD-ITU-T RECMN TnbZ-ENGL 1773 m 48b2571 Ob2004b 248 m INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEMATIC SERVICES TERMINAL EQUIPMENTS AND PROTOCOLS FOR TELEMATIC SERVICES T.62 (03/93) CONTROL PROCEDURES FOR TELETEX AND GROUP 4 FACSIMILE SERVICES I

2、TU-T Recommendation T.62 (Previously “CCITT Recommendation”) FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendati

3、ons on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. ITU

4、-T Recommendation T.62 was revised by the ITU-T Study Group VI11 (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place,

5、 the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to ref

6、erences containing the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operating ag

7、ency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 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 perm

8、ission in writing from the ITU. CONTENTS General . 1.1 Scope 1.2 Fundamental principles . 1.3 Definitions Functions of the procedures . 2.1 General 2.2 Background information . Elements of procedure Session commands, responses and parameters . Document commands, responses and parameters . General ru

9、les for document elements of procedure Error recovery 4.1 General principles . 3.1 General 3.2 3.3 Session procedures 3.4 3.5 3.6 Rules for document state diagrams . 4.2 Rules for checkpointing 4.3 Acknowledgement window Coding 5.1 5.2 Principles of coding 5.3 Coding of length indicators 5.4 Coding

10、of command and response identifiers for session elements . 5.5 Coding of command and response identifiers for document elements . 5.6 Coding of parameter group identifiers and parameter identifiers . 5.7 Parameter values . Definition of terms used in coding . Annex A . Definitions . A.l General A.2

11、Terms specific to session procedures A.3 Terms specific to document procedures . Annex B - Telematic modes of operation B.l Introduction B.2 Telematic modes of operation . B.3 Relationship between Telematic modes of operation and the OS1 session services . Annex C - Definition of validhnvalid sessio

12、n protocol data units . C.l Introduction C.2 Invalid protocol data units (PDUs) (definition and rules) C.3 Valid PDUs (rules for mandatory acceptance of PDUs) Annex D - General description and rules of operation for state diagrams . Recommendation T.62 (03/93) Page 1 1 1 2 2 2 4 4 4 4 8 9 15 16 19 1

13、9 19 20 21 21 21 24 25 25 25 28 40 40 41 42 43 43 43 43 45 45 45 45 46 i STD.1Tl.J-T RECMN T-b2-ENGL 1993 LiAb2571 Ub20047 T57 = Annex E . Types of document . . E . 1 General E.2 Normal document E.4 Control document . E.3 Operator document (optional) . ES Monitor document (optional) . Annex F - Inte

14、ractive session protocol and typed data transfer for the Telematic services . Annex G - Detailed state transition diagrams for session/document procedures . G . 1 General G.2 Description on notations . . G.3 Service primitives . G.4 Detailed state transition diagrams for the basic services Annex H -

15、 State transition tables for sessioddocument procedures H . 1 General H.2 Notation details . H.3 State tables Page 47 47 47 47 47 47 48 48 48 48 50 55 60 60 60 61 11 Recommendation T.62 (03/93) STD-ITU-T RECMN T-bZ-ENGL 1993 48b2591 Ob20050 777 Recommendation T.62 CONTROL PROCEDURES FOR TELETEX AND

16、GROUP 4 FACSIMILE SERVICES (Malaga-Torremolinos, 1984; amended at Melbourne, 1988 and at Helsinki, 1993) 1 General 1.1 Scope 1.1.1 Recommendation F.200 lays down the provisions for the operation of the automatic international Teletex service. On the technical side, Recommendation T.60 specifies the

17、requirements for international compatibility between Teletex terminals and Recommendation T.61 defines the character repertoire and coded character sets for the international Teletex service. 1.1.2 Recommendation F.161 defines the rules to be followed in the Group 4 facsimile service. On the technic

18、al side, Recommendations T.563, T.503 and T.521 specify the requirements for Group 4 facsimile apparatus and Recommendation T.6 defines the Group 4 facsimile coding scheme and facsimile control functions. 1.1.3 services other than basic Teletex are utilized; e.g. Group 4 facsimile, mixed-mode operat

19、ion, etc. The T.400 - Series Recommendations define the document interchange protocol which may be used when 1.1.4 Network-dependent communication procedures for call establishment and termination are defined in Recommendations T.60 and T.563 for the Teletex and Group 4 facsimile services, respectiv

20、ely. 1.1.5 services. This Recommendation defines the end-to-end procedures to be used within the Teletex and Group 4 facsimile 1.1.6 Specifically, this Recommendation concerns the end-to-end control procedures that are network-independent. The network-dependent procedures forming a network-independe

21、nt transport service are specified in Recommendations T.70 and, as applicable, T.71. 1.1.7 The procedure described in this Recommendation should also be used between a Teletex terminal and a Teletedtelex conversion facility (see Recommendations F.201, T.60 and T.390) and when a Teletex or G4 facsimi

22、le terminal takes an access to IPMS (see Recommendations F.422, T.60, T.330 and T.563). 1.1.8 services other than IPMS is for further study. Interworking between Teletex and services other than telex and IPMS, and between Group 4 facsimile and 1.1.9 charges and that it retains full control of the ca

23、ll. This Recommendation assumes that the terminal initiating a call is the terminal regarded as responsible for call 1.1.10 The provisions in this Recommendation are to be regarded as a first stage in the establishment of Teletex and Group 4 facsimile services in accordance with Recommendations F.20

24、0, T.60, T.61 and T.70 as defined in 1980 and Recommendations F.161, T.5, T.6 and T.73 as defined in 1984, respectively. Enhancements and additions to these Recommendations must ensure compatibility with established services. 1.2 Fundamental principles 1.2.1 The relationship between the control proc

25、edures in this Recommendation and the transport service shall respect the principle that the higher level procedures require the transport service to preserve the structure of blocks, which may be of arbitrary size, given to it by the session level for transmission. Only one session command or respo

26、nse is allowed in such a block. Only one document command or response is allowed in a CSUI or RSUI field (command or response session user information). 1.2.2 recipients physical media, i.e. stoi,e, hard copy device. This may include linking and other relevant information. The sending terminal is re

27、sponsible for verifying the correct delivery of the information in its document to the Recommendation T.62 (03193) 1 STD-ITU-T RECMN T*bZ-ENGL 1773 48b257L Ob2005L b05 Command 1.3 Definitions Response 1.3.1 procedures to which it refers. Terms and their definitions are listed in Annex A. Where appro

28、priate, each definition mentions the control 1.3.2 of similar terms in other Recommendations. Some of the terms used in this Recommendation have been defined in ways that may differ from the meanings 2 Functions of the procedures 2.1 General 2.1.1 The broad functional categories provided to implemen

29、t the control procedures are listed in Tables 1 and 2. Zommand session start Command session end Command session abort Response session start positive Response session start negative Response session end positive Response session abort positive Information transfer Command session user information R

30、esponse session user information Session management Command session change control Response session change control positive Abbreviation css RSSP RSSN CSE RSEP CSA RS AP CSUI RSUI cscc RSCCP Reference (subclause) 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 3.2.9 3.2.10 3.2.1 1 2 Recommendation T

31、.62 (03/93) STD-ITU-T RECMN TmbZ-ENGL 1773 48b2571 b20052 541 W TABLE 2E.62 Document commands and responses Command Response Command document start Command document continue Commande document capability list Command document end Command document discard Command document resynchronize I Document cont

32、rol Response document capability list positive Response document end positive Response document discard positive Response document resynchomize positive Information transfer Command document user information Error recovery Command document page boundary Response document general reject Response docu

33、ment page boundary positive Response document page boundary negative Abbreviation CDSa) CDCa) CDCL RDCLP CDE) RDEP CDD RDDP CDR RDRP CDUI RDGR CDPB RDPBP RDPBN a) b, RDGR is used as a negative response to this command. A specific negative response is not required. The negative response to this comma

34、nd is RDPBN. Reference (subclause) 3.4.1 3.4.3 3.4.4 3.4.5 3.4.6 3.4.7 3.4.8 3.4.9 3.4.10 3.4.1 1 3.4.12 3.4.2 3.4.13 3.4.14 3.4.15 2.1.2 elements together with their associated rules completely specifj the functions of the procedures. The procedural elements have also been listed in the appropriate

35、 categories since the definitions of the Recommendation T.62 (03/93) 3 STD*ITU-T RECMN T-b2-ENGL 1793 m Li8b2591 Ob20053 Li88 m 2.2 Background information are given in subsequent Clauses of the Recommendation. NOTE - Clause 2 is given as an aid for the understanding of the procedures. The exact defi

36、nitions of the control procedures 2.2.1 Exchange of service identification 2.2.1.1 Two terminals, when connected by a transport service, will, at session establishment, exchange information identifying whether they are participating in the Telematic services and thus they will invoke the relevant se

37、rvice facilities and the associated protocol. 2.2.2 Negotiation of optional capabilities 2.2.2.1 Two methods are provided. The first is used at session initiation to exchange a limited list of capabilities. The second method may be used when required, after session initiation, to indicate the sender

38、s requirements for extended capabilities. 2.2.3 Negotiation of storage requirements 2.2.3.1 Storage availability can be indicated in the following ways: a) When a Teletex session is established, it is implicitly assumed that there is adequate receive memory for the call. Exceptionally a receiver mem

39、ory overflow will occur. The continued sending of the document from the source will be stopped by the sink. The sink shall indicate the reason for stopping the transmission. When a Group 4 facsimile session is established, it can only be assumed that the called terminal has adequate recording paper

40、to print at least one page of information (for basic Class 1 apparatus). Negotiation of storage requirements is mandatory for Group 4 Classes 2 and 3 facsimile apparatus. Having negotiated this requirement, exceptionally, a receive memory overflow may occur. The continued sending of the document fro

41、m the source will be stopped by the sink. The sink shall indicate the reason for stopping the transmission. The provision is also made in the procedure for a mandatory indication that the ability of the receiving terminal to continue to accept traffic is jeopardized. The control procedure also provi

42、des the possibility to investigate the storage availability at the receiving terminal prior to the transmission of a document. b) c) d) 3 Elements of procedure 3.1 General 3.1.1 control procedures. 3.1.2 3.1.3 The subclauses below contain elements of procedure and rules of use which, when combined,

43、define the Definitions applying to the elements of procedure may be found in Annexes A and B. Annex D describes the session suspension function, which is not applicable to the basic services. 3.2 (For a summary of session commands and responses, see Table i .) Session commands, responses and paramet

44、ers 3.2.1 Command session start (CSS) 3.2.1.1 3.2.1.2 Command parameters are: The CSS initiates entry into a session. a) Service identifier - This mandatory parameter identifies whether the sender of this command intends to use the Telematic service. b) Terminal identifier - This mandatory parameter

45、 identifies the calling terminal in accordance with the terminal identification specified in Recommendation F.200. c) Date and time - This mandatory parameter gives date and time information as specified in Recommendation F.200. 4 Recommendation T.62 (03/93) f, Parameter Additional session reference

46、 number - This number shall be used in addition to the basic session reference (terminal identifier of the called terminal, terminal identifier of the calling terminal, date and time) when the basic session reference is not sufficient to uniquely identify the session and such unique identification i

47、s required. If the additional session reference number is not used, the parameter shall not be included. Non-basic terminal capabilities - These parameters indicate which of the non-basic terminal capabilities listed in Table 3 for the Teletex service are available as receiving capabilities of the s

48、ender of this command. These parameters are mandatory if the terminal is capable of any of the specific functions listed in this table. Absence of the parameter indicates that the specific function is not available. Non-basic session cupubifities - If used, this non-mandatory parameter indicates whi

49、ch non-basic session capabilities are available as receiving capabilities of the sender of this command. NOTE - Examples of the use of this parameter are session suspension (see Annex D) and negotiation of the window size for checkpoint (see 3.3.2.7 and 4.3). Inactivity timer - This non-mandatory parameter is used to negotiate the value of the inactivity timer (see 4.1.2 and 5.7.2.11). Session service functions - This non-mandatory parameter is used to specify the session service capabilities available. This parameter is used for the interactive session protocol (ISP) and typed