1、CCITT RECMN*F-30 93 m 4862593 0576993 535 m INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU OPERATIONS AND QUALITY OF SERVICE TELEGRAPH SERVICES F.30 (03/93) USE OF VARIOUS SEQUENCES OF COMBINATIONS FOR SPECIAL PURPOSES ITU-T Recommendation F.30 (Previousl
2、y “CCITT Recommendation”) CCITT RECMN*F=30 93 4862593 0576972 Y53 FOREWORD The ITU Telecommunication Standardization Sector (1721-T) is a permanent organ of the International Telecom- munication Union. The 1721-T is responsible for studying technical, operating and tariff questions and issuing Recom
3、mendations 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 topi
4、cs. ITU-T Recommendation F.30 was revised by the IT-T Study Group I (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 pla
5、ce, the I721 Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the FRI3 have been replaced by the Radiocommunication Sector.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
6、 references containing the acronyms “CCITT, CClR 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 operatin
7、g agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, elecuonic or mechanical, including photocopying and microfilm, without p
8、ermission in writing from the ITU. CCITT RECMNxF.30 93 m Y862571 057b993 398 m Recommendation F30 USE OF VARIOUS SEQUENCES OF COMBINATIONS FOR SPECIAL PURPOSES (Melbourne, 1988; revised Helsinki, 1993) The CCITT, unanimously declares that 1) when it is necessary to provide for switching of telegrams
9、 to different routes in semi-automatic or fuiiy automatic telegram retransmission systems, the beginning and ending of each telegram are identified by the insertion of start-of-message and end-of-message signals; 2) the start-of-message signal consists of the sequence ZCZC in letter case; 3) the end
10、-of-message signal consists of the sequence “N, in letter case; 4) the equipment that recognizes the start-of-message and end-of-message signals may be designed to do so by searching only for the sequence of four combinations corresponding to ZCZC or NNNN respectively (i.e. combinations 26, 3, 26, 3
11、 or 14, 14, 14, 14 in International Telegraph Alphabet No. 2 regardless of whether they are in letter or figure case); 5) Table 1 lists other sequences of combinations used for special purposes. Recommendation F.30 (03D3) 1 CCITT RECMN*F-30 93 4862593 057b994 224 = 11 11 11 11 11 12 11 12 Purpose of
12、 sequence KKKK ( R.79, R.79 bis KLKLA O0 s .4 Connection of reperforator Disconnection of reperforator or eauivalent device) 14 14 14 14 19 19 19 19 I Suppression of delay signals NNNN 9979 F.l, F.31, S.4, U.22 ssss S.15 IIII Switching a reader (or equivalent device) into circuit by remote control 2
13、6 3 26 3 26 26 26 26 End of message or enabling of delay Change of alphabet zczc +: +: F.l, F.31 zzzz + F.200 I Error signal 13 13 13 13 (Note 2) (Note3) 1 MMMM (Note 3) 1 Start of message End of input s.4, u.44 Request for automatic advice of parties cleared prematurely during the broadcast cai1 fo
14、llowed by call cleared 20 20 20 . (Note 4) 10 (Notes 4 and 5) Operator recall over radiotelegraph circuit T T T . 5 5 5 1 s .4 (Note 4) (Notes 4 and 5) J. a s.4, s.22 JL Stop transmission from distant auto terminal interngation of distant terminal I Follow-on call TABLE 1LF.30 Printed position Lette
15、r case Figure case Recommendation reference Sequence of combination 6666 (Note 1) 8888 HHHH (Note 1) s.4, u.22 2424242424 I XXXXX I Illll I F.l (C111) 12121212 I LLLL I )I) I s.4,u.43 I NOTES 1 Administration. 2 3 4 Repeated if necessagr. 5 6 See also Table 2K.1. As noted in C5S.1, the figure case o
16、f combinations 6, 7 and 8 is available for the internal service of each As noted in Recommendation U.44 this sequence is to be recognized in letter case only. A minimum of 4 Ms would clear a telex broadcast call. The usage of a 5th or more Ms is a national matter. Function only applicable in figure case. 2 Recommendation F.30 (0-3) CCITT RECMN*F-30 93 m 48b259L 05b995 LbO = Printed in Switzerland Geneva, 1993
