1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 3 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(9!,0(!“%4)#!,G0G04%,%2!0(G0G04%2-).!,%15)0-%.4#/.6%23)/.G0G0“%47%.G0G0).4%2.!4)/.!,4%,%2!0(G0G0!,0(!“%4G0G0.O G0 G0G0!.$).4%2.!4)/.!,G0G0!,0(!“%4G0G0.O G0 )45G134G0G0RecommendationG0G03 (Extract from
2、the “LUEG0“OOK)NOTES1 ITU-T Recommendation S.18 was published in Fascicle VII.1 of the Blue Book. This file is an extract from theBlue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book ve
3、rsion and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be re
4、produced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VII.1 - Rec. S.18 1Recommendation S.18Fascicle VII.1 - Rec. S.18CONVERSION BETWEEN INTERNATIONAL TELEGRAPH ALPHABETNo. 2 AND INTERNATIO
5、NAL ALPHABET No. 5(Geneva, 1980)The CCITT,considering(a) that the Recommendation cited in 1 defines International Telegraph Alphabet No. 2 (ITA2), which isused, for example, in the international telex service;(b) that International Alphabet No. 5 (IA5), defined in Recommendation T.50 2, has been est
6、ablished jointlyby the CCITT and the International Organization for Standardization (ISO) for use in data transmission (for example);(c) that rules for converting from ITA2 to IA5 and vice versa are desirable to facilitate interworking, forexample between terminals in the international telex service
7、 and terminals in data networks;(d) that a suitable set of rules has been drawn up in collaboration with ISO;(e) that for specific user applications some variations in the tables below may be developed and applied bybilateral agreement;(f) that this Recommendation does not define whether the alphabe
8、tic characters of ITA2 are represented ascapital or small letters;unanimously recommendsthat the following rules for conversion should apply.1 Conversion from ITA2 to IA51.1 The conversion of characters shall be as specified in Table 1/S.18.1.2 Annex A, together with Table A-1/S.18, provides informa
9、tion on alternative conversions that are in general usein some countries.2 Conversion from IA5 to ITA22.1 The conversion of characters shall be as specified in Table 2/S.18.2.2 The control characters of positions 0/1, 0/2, 0/3, 0/4, 0/6, 1/0, 1/5, 1/6 and 1/7 are generally not convertedbecause they
10、are removed from the character string by the link control equipment.2.3 Characters for which there are no direct equivalents shall be represented by the single character question mark(?), unless prior agreement has been made between the interchange parties.2.4 The greater number of code combinations
11、 available in IA5 means that not every character can be translatedunambiguously into a single ITA2 character. Use of a single character, rather than a multi-character representation, willminimize formatting problems.2.5 Annex A together with Table A-2/S.18 provide information on some alternative con
12、versions that are in use insome countries.2 Fascicle VII.1 - Rec. S.18TABLE 1/S.18Conversion from ITA2 to IA5ITA 2 ITA 2IA 5ITA 2IA 5combination letterCharacter Coding Character CodingfigureCharacter Codingnumber case(See Note 3) (See Note 3)case1234567891011121314151617181920212223242526ABCDEFGHIJK
13、LMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ4/14/24/34/44/54/64/74/84/94/04/114/124/134/144/155/05/15/25/35/45/55/65/75/85/95/10abcdefghijklmnopqrstuvwxyz6/16/26/36/46/56/66/76/86/96/106/116/126/136/146/157/07/17/27/37/47/57/67/77/87/97/10?:WRU3National useNational useNational use8BELL().,901457=2/6+?:
14、ENQ (SeeNote 1)3(See Note 4)8BEL().,901457=2/6+2/133/153/100/53/33/80/72/82/92/142/123/93/03/13/42/73/53/73/133/22/153/62/11ITA 2combination numberITA 2 character(either case)IA5 characterIA5coding272829303132Carriage-returnLine-feedLetter-shiftFigure-shiftSpaceNot normally usedFE5FE2(See Note 2)(Se
15、e Note 2)SP(See Note 4)0/130/102/00/0Note 1 This character is used only to operate the answer-back unit of the corresponding instrument in the international publicservices.Note 2 These characters have no corresponding function in IA5. Conversion equipment operates the appropriate shift and discardst
16、he characters.Note 3 Small or capital letters may be used, however intermixing of small and capital letters is not allowed.Note 4 These characters have no international allocation.Fascicle VII.1 - Rec. S.18 3 4 Fascicle VII.1 - Rec. S.18ANNEX A(to Recommendation S.18)Alternative conversions between
17、IA5 and ITA2A.1 Recommendation S.18 permits alternative conversions for characters that have no direct equivalents, providedthese conversions are agreed between interchange parties. Other alternatives may be used.A.2 Tables A-1/S.18 and A-2/S.18 list conversions that are in use in some countries.A.3
18、 In some nationally adapted applications of ITA2 and IA5, special conversion rules are required becausenational characters have been allocated in different orders in the coded character sets concerned.A.4 NUL is equivalent to all space (combination No. 32 or NU) in ITA2.TABLE A-1/S.18Examples of alt
19、ernative conversions from ITA2 to IA5ITA 2 IA 5Alter-na-tiveCase Combination No. Character Character Code Remarksa) FigureFigureFigure678National useSUBSUBSUB1/101/101/10b) FigureFigureFigure678National use5/115/125/13See A.3c) FigureFigureFigure678National use7/117/127/13See A.3d) Either 29 Letter
20、shift IS21/14Either 30 Figure shift IS11/15e) Either 29 Letter shift DEL 7/15Either 30 Figure shift DEL 7/15f) As e) but with additional agreement that only shift characters following the first one are converted to 7/15. The first one is treated accordingto Table 1/S.18.g) Either 32 NU NUL 0/0 See A
21、.4Fascicle VII.1 - Rec. S.18 5TABLE A-2/S.18Examples of alternative conversions from IA5 to ITA2IA 5 ITA 2 RemarksCode Character Characters Combinations0/0 NUL NU 32 See A.40/10/20/30/40/61/11/51/61/7SOHSTXETXEOTACKDLENAKSYNETB)?)12 (right parenthesis)2 (question marks)12 (right parenthesis)in figur
22、e caseAlternative conversions where charactersnot removed from the character string bythe link control equipment or by convention0/80/90/110/120/140/151/11/21/31/41/81/91/101/111/121/13FE0FE1FE3FE4SOSIDC1DC2DC3DC4CANEMSUBESCIS4IS3)?)12 (right parenthesis)2 (question mark)12 (right parenthesis)in fig
23、ure case1/141/15IS2IS1Letter-shiftFigure-shift2930See also Table A-1/S.18. Combinations 29and 30 may be used with either case2/12/22/32/42/52/62/103/113/123/144/05/145/156/07/117/127/137/14!“#%_)?)11 (left parenthesis)2 (question mark)12 (right parenthesis)in figure case5/115/125/13National use opti
24、ons678in figure case See A.37/117/127/13National use options678in figure case See A.37/15 DEL Letter-shift 29Note Use of new line requires additional agreement between the interchange parties.6 Fascicle VII.1 - Rec. S.18References1 CCITT Recommendation Operational provisions for the international public telegram service, Rec. F.1, C.2 CCITT Recommendation International Alphabet No. 5, Rec. T.50.
