7_3_01.txt

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                              FASCICLE VII.3






                            Recommendations T.0-T.63





                        TERMINAL EQUIPMENT AND PROTOCOLS

                             FOR TELEMATIC SERVICES



                                                                     Blanc





       MONTAGE:  PAGE 2 = PAGE BLANCHE



          "Telematic services" is used provisionally and includes such
                 services as Videotex, Teletex, facsimile, etc.




                           COLLABORATION WITH OTHER  |
                          INTERNATIONAL ORGANIZATIONS

                      ON CCITT-DEFINED TELEMATIC  SERVICES

             Recommendation A.21 published in Volume I is reproduced


                    below for the convenience of the reader.





       Recommendation A.21

              COLLABORATION WITH OTHER INTERNATIONAL ORGANIZATIONS



                      ON CCITT-DEFINED TELEMATIC SERVICES

              (Geneva, 1980, amended at Malaga-Torremolinos, 1984)



               The CCITT,











       considering


            (a) that, according to Article 1 of the agreement between  the
       United  Nations  and the International Telecommunication Union, the
       United Nations recognizes the International Telecommunication Union
       as the specialized agency responsible for taking such action as may
       be appropriate under its basic instrument for the accomplishment of
       the purposes set forth therein;

            (b) that Article 4 of the International Telecommunication Con-
       vention   |  (Nairobi,  1982) states that the purposes of the Union
       are:

                "a)  to  maintain  and  extend  international  cooperation
       between  all  Members of the Union for the improvement and rational
       use of telecommunications of all kinds, as well as to  promote  and
       to  offer technical assistance to developing countries in the field
       of telecommunications;

               " b)      to promote the development of  technical  facili-
       ties  and  their  most efficient operation with a view to improving
       the efficiency of telecommunication services, increasing their use-
       fulness and making them, as far as possible, generally available to
       the public;

               " c)      to  harmonize  the  actions  of  nations  in  the
       attainment of those ends.";

            (c) that Article 40 of the Convention states that "in further-
       ance  of  complete  international coordination on matters affecting
       telecommunication, the Union  shall  cooperate  with  international
       organizations having related interests and activities";

            (d) that this cooperation has to recognize the advisory  capa-
       city of organizations participating in the work of CCITT;

            (e) that, in the study  of  terminals  for  new  CCITT-defined
       telematic   services  (e.g. for  Teletex  ,  Telefax  ,  Datafax  ,
       Bureaufax , Videotex services), ISO in  particular  is  invited  to
       give  advice  to CCITT based on their work on data systems and data
       communications;


            (f ) that this cooperation has to be  organized  in  a  manner
       that  will avoid duplication of work and of decisions that would be
       contrary to the principles set out above;


       recognizes the following principles


            (1) It is the responsibility of the CCITT alone  to  make  the
       decisions  regarding  the operational, technical (including factors
       needed to ensure international interworking) and tariff  principles
       of the CCITT-defined services.










            (2) While the CCITT will define many of the  relevant  factors
       for  the  CCITT-defined  telematic  services,  other  international
       organizations will be invited to give specialist advice to CCITT on
       subjects that are of mutual interest, such as:

               -         character sets and coding;

               -         end-to-end  control  procedures  including  error
       protection;

               -         interfaces between  terminals  and  circuit  ter-
       minating equipment;

               -         terminal transmitter distortion and receiver mar-
       gin;

               -         paper sizes and text formatting.

            (3) Standardization, if required,  of  hardware  and  software
       implementation  of terminals, such as printing systems, paper feed,
       character type fonts, paper characteristics, etc., are outside  the
       scope of CCITT.


       Recommendation A.22

              COLLABORATION WITH OTHER INTERNATIONAL ORGANIZATIONS



                           ON INFORMATION TECHNOLOGY

                               (Melbourne, 1988)



               The CCITT,



       considering


            (a) that the purposes of the  International  Telecommunication
       Union  and  the recognition of CCITT relations with other organiza-
       tions were given in 1964 and later,  in  CCITT  Recommendation A.20
       which concerns data transmission;

            (b)  that  the  principles  of  responsibility  in  regard  to
       CCITT-defined  Telematic  services were given in 1980 and later, in
       Recommendation A.21  which  mentions  some   subjects   of   mutual
       interest;

            (c) that CCITT Resolution No. 7  in  1984  further  recognized
       common interests with ISO and IEC concerning Information Technology
       and cooperation with them by appropriate means,










       recognizes the following principles


            (1) that in accordance  with  CCITT  Recommendations A.20  and
       A.21  and  Resolution  No. 7, every effort should be made in estab-
       lishing respective study programmes to identify overlapping studies
       with a view to avoiding duplication of work;

            (2) that where subjects are identified in  which  coordination
       seems desirable, text should be drawn up mutually and kept aligned;

            (3) that in carrying on the respective programmes of  Informa-
       tion Technology studies, collaborative meetings at appropriate lev-
       els should be scheduled, where necessary. In drafting aligned text,
       it  is  necessary  to  take  into account the respective timing for
       approvals and publication,  particularly  with  the  ISO/IEC  Joint
       Technical Committee 1 (JTC1) on Information Technology;


            (4) that commonality of text with ISO/IEC and cross-references
       is  considered  desirable in certain areas of mutual interest, such
       as:

               -         Message Handling Systems,

               -         Directory Systems,

               -         Open Systems Interconnection (OSI) architecture -
       service definitions and protocol specifications,

               -         certain areas of Interworking,

               -         certain aspects of Telematic Services,

               -         Document Architecture,

               -         certain aspects of ISDN.


       Recommendation T.0

             CLASSIFICATION OF  FACSIMILE APPARATUS FOR DOCUMENT  |
                                  TRANSMISSION



                            OVER THE PUBLIC NETWORKS

                    (Geneva, 1976; amended at Geneva, 1980;


                 Malaga-Torremolinos, 1984 and Melbourne, 1988)


            1 For document facsimile transmission by international commun-
       ications carried on the public networks there is a need for provid-
       ing sufficient operating speeds to meet users' requirements.









            2 Users' requirements may best be served at the  present  time
       by classifying the following four basic categories of document fac-
       simile apparatus.



       2.1         Apparatus for use over the public telephone network



               Group 1  (see Note 1)


            Apparatus which uses double sideband  modulation  without  any
       special  measures to compress the bandwidth of the transmitted sig-
       nal and which is suitable for  the  transmission  of  documents  of
       ISO A4  size at nominally 4 lines per mm in about six minutes via a
       telephone-type circuit.

            Apparatus in this group may be designed to operate at a  lower
       definition  suitable  for  the  transmission of documents of ISO A4
       size in a time between three and six minutes.


               Group 2  (see Note 2)


            Apparatus which exploits bandwidth compression  techniques  in
       order to achieve a transmission time of about three minutes for the
       transmission of an ISO   A4  size  document  at  nominally  4 lines
       per mm via a telephone-type circuit.  Bandwidth compression in this
       context includes encoding and/or  vestigial  sideband  working  but
       excludes processing of the document signal to reduce redundancy.


               Group 3  (see Note 3)


            Apparatus which incorporates means for reducing the  redundant
       information  in the document signal prior to the modulation process
       and which can achieve a transmission time of about 1 minute  for  a
       typical  typescript  document  of  ISO A4 size via a telephone-type
       circuit. The apparatus may incorporate bandwidth compression of the
       line signal.



       2.2         Apparatus for use over the public data networks



               Group 4  (see Note 4)


            Apparatus which incorporates means for reducing the  redundant
       information in the document signal prior to transmission mainly via
       public data networks (PDNs). The apparatus will utilize  procedures









       applicable  to  the  PDN  and will assure an essentially error-free
       reception of the document. The apparatus may also be  used  on  the
       public  telephone  network  where an appropriate modulation process
       will be utilized.

            3 The users will choose among this  apparatus,  in  accordance
       with  their needs and the facilities afforded by the connection and
       the network.


            4  Procedures  for  Groups 1,  2  and 3   document   facsimile
       transmission  in the public switched telephone network should be in
       accordance with Recommendation T.30.


            5  Procedures  for  Group 4  document  facsimile  transmission
       should  be  in accordance with Recommendations T.62, T.62 | fIbis ,
       and T.70.


            Note 1    - This   apparatus   has   been   standardized    in
       Recommendation T.2.

            Note 2    - This   apparatus   has   been   standardized    in
       Recommendation T.3.

            Note 3    - This   apparatus   has   been   standardized    in
       Recommendation T.4.

            Note 4    - This   apparatus   has   been   standardized    in
       Recommendations T.6, T.503, T.521 and T.563.

            6 Annex A contains definitions for terms used in the  T-series
       Recommendations applicable to facsimile apparatus.

                                     ANNEX A
                             (to Recommendation T.0)

           Definitions for terms used in the T-series Recommendations

                       applicable to fascimile apparatus

            The following definitions apply to Recommendations  T.1,  T.2,
       T.3   and T.4:



       A.1         dead sector (Recommendations T.1, T.2)


            In drum apparatus, that portion of the drum surface the  scan-
       ning time of which cannot be used for picture signal transmission.


       A.2         drum factor (Recommendation T.1)











            In drum apparatus, the ratio of the usable scanning length  of
       the drum to its diameter.