ITU-T F 21-1993 COMPOSITION OF ANSWER - BACK CODES FOR THE INTERNATIONAL GENTEX SERVICE《国际电路公众电报业务用的应答码的组成》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 (b) that the answer-back code in the international gentex service should therefore include the call-number ofthe office and as much of the name of this office as possible;(c) that it is also essential to show in the answer-back code one or two characteris

2、tic letters of the country inwhich the teleprinter equipment is situated, for the worst routing mistake is that of sending a telegram to the wrongcountry;(d) that Administrations may identify, by additional letters in the answer-back code, not only the office butalso the nature of the position in th

3、e office (outgoing position, incoming position), or the identity of the position amongall similarly specialized positions, so as to facilitate the location of any faults in the equipment of the tracing of anytelegrams in disupute;(e) that the initial letters of the alphabet: A, B, C, etc., are to be

4、 used for identifying specialized outgoingpositions and one of the final letters of the alphabet Z, Y, X, etc. for identifying specialized incoming positions. Forvery large offices, where groups of machines having the same specialized function, outgoing or incoming, maycomprise more than 12 machines

5、, it will be necessary to use additional specialization letters:T to indicate a position specializing in transmission;R to indicate a position specializing in reception;(f) that if an office that uses letters denoting specialization is also equipped with combined incoming/outgoingpositions, such pos

6、itions will be identified by the same specialization letter as the incoming positions;(g) that should outgoing or incoming groups comprise more than 26 machines, the letters S and Q, denotingoutgoing or incoming specialization respectively, may be used in conjunction with the letters T and R, thus i

7、ncreasingthe possibility of identification in a group of machines to 52;(h) that in the case of overflow positions, they must indicate very clearly the name of the office obtained, forthis name belongs to an office other than the one called. For this purpose, the call-number of the overflow office w

8、illnot appear in the answer-back code of such a position, so as to leave space for the name of the office as complete aspossible and the characteristic indication DEB, which has been chosen to denote overflow;(i) that because machines in the gentex service can be page-printing machines, it is necess

9、ary to providecarriage-return and line-feed signals at the beginning of the answer-back code and for technical reasons the lastcharacter of the answer-back code must be the letter-shift signal,unanimously declares(1) that answer-back codes of machines used in the international gentex service should

10、be made up of20 signals;(2) that, for machines other than those used on positions specialized for receiving overflow traffic, the seriesof 20 signals in the answer-back code should, in principle, be as follows: carriage-return, line-feed, figure-shift,2 Fascicle II.4 - Rec. F.21 the figures of the c

11、all-number by which the office is to be called when a telegram is sent to it in some largeoffices a position (or group of positions) may specialize in dealing with service advices, and in this case itis provided with a special call-number and answer-back code see (6) below, letter-shift, space, lett

12、ers indicating as explicitly as possible the name of the office, space, the characteristic letters of the name of the country, in accordance with the code listed under (9) below, letter-shift.Note Some teleprinters are permanently arranged to transmit letter-shift as the first character of the answe

13、r-back. In this case the letter-shift should precede the carriage-return and will reduce the number of characters availablefor the name of the office by one.(3) that, for Administrations that wish to give the specialization and identity of the positions with whichequipment is associated in large off

14、ices, the series of 20 signals in the answer-back code should be made up as follows,according to the size of such offices: carriage-return, line-feed, figure-shift, the call number as indicated under (2), letter-shift, one or two letters chosen in accordance with Table 1/F.21, space, the name of the

15、 office, space, the characteristic letters of the name of the country, letter shift;(4) if, in the exchanges referred to in (3) above, combined incoming/outgoing positions are used in additionto specialized incoming or outgoing positions, the answer-back codes of these combined positions should be c

16、omposedin the same way as the answer-back codes of a specialized incoming position;(5) The specialization letter T should be preferred to the letter S, and the letter R to the letter Q; the letters Sand Q should be used only when such use is justified by the exchange equipment;Fascicle II.4 - Rec. F

17、.21 3TABLE 1/F.21Size of officeFor a specializedoutgoingpositionFor a specializedincomingpositionLarge officeone letterfrom A to Lone letterfrom Z to OVery large officethe letter Tandone letter fromA to Zthe letter Randone letter fromA to ZExceptionallylarge officethe letter T orthe letter Sandone l

18、etter fromA to Zthe letter R orthe letter Qandone letter fromA to Z(6) that, for the positions specialized in dealing with service messages, the series of 20 signals of the answer-back code should be as follows: carriage-return, line-feed, figure-shift, the call-number of the specialized position or

19、 group of positions, letter-shift, space, the name of the office, space, letters INQ, letter-shift;(7) that, for positions specialized in the reception of overflow traffic, the series of 20 signals in the answer-back code should be as follows: carriage-return, line-feed, letter-shift, position ident

20、ification letter(s), space, the name of the office, space, letters DEB, letter-shift;(8) that, if an answer-back code does not fill the 20 places available, the unused places should be filled by thenecessary number of space signals between the name of the office and the country code;4 Fascicle II.4

21、- Rec. F.21(9) that the characteristic letters of names of countries should be the same as the telex network identificationcode shown in the List of Destination Indicators and Telex Network Identification Codes 1 with the exception of thecountries below, which use the characteristic letters shown:CS Czechoslovakia I ItalyGB United Kingdom L LuxembourgReference1 List of indicators for the telegram retransmission system and telex network identification codes, ITU, Geneva.