ITU-T U 74-1988 EXTRACTION OF TELEX SELECTION INFORMATION FROM A CALLING TELEX ANSWERBACK《从一个主叫用户电报应答中提取用户电报选择信息》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 5 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(G0G037)4#().).4%27/2+).G0G0“%47%.G0G0.%7G0G0). amended at Melbourne, 1988)The CCITT,considering(a) that there is a need for automatic address extraction from a telex answerback (e.g. access to atelex-

2、Teletex conversion facility (CF) or an SFU);(b) that Recommendation F.60 defines a preferred structure for the telex answerback;(c) that different forms of answerbacks exist;(d) that Recommendation F.60 bis defines a structure for a telex answerback associated with anintermediate document storage de

3、vice,unanimously declaresthat answerbacks are considered “technically processable” (i.e., the answerback can be interpretedunambiguously to determine the F.69 code and national call number) if they contain the minimum fields defined inRecommendation F.60, separated by detectable delimiters, with all

4、owance made for the following additions: F.60 fields may or may not be in the preferred order; the Telex Network Identification Code (TNIC) should be preceded and succeeded by detectable delimiters:i) preceding delimiters are national call number and space,ii) succeeding delimiters are national call

5、 number, space or end of answerback (end of answerback meansno more printable characters); one hyphen or one space with the national call number is ignored; the corresponding international access code for the “J” TNIC is:i) 72, if the national call number consists of 5 digits,ii) 720, if the nationa

6、l call number consists of less or more than 5 digits.The international access code for all other TNICs follows Recommendation F.69. For conversion betweenTNICs and F.69 codes, see also Recommendation F.69.An algorithm which meets the preceding criteria is shown in Figure 1/U.74.2 Fascicle VII.2 - Re

7、c. U.74 Fascicle VII.2 - Rec. U.74 3Note 1 Cheek the automatic emitting speed and wait for the end of the answerback. The answerback is consideredto have ended after detection of a 300 ms period of idle.Note 2 “Retry” refers to another attempt to trigger the answerback.Note 3 Printable figures are c

8、ombination No. 17 (1) to combination No. 16 (0). Spaces (combination No. 31),hyphens (combination No. 1) and equal signs (combination no. 22) are allowed in this field, but are ignored.Note 4 Are there one or two printable letters at the end of the answerback, preceded by a space?Note 5 Are there on

9、e or two printable letters following immediately the “national call number” (without spacebetween), with space after them?Note 6 In the case of a letter code single “J” corresponding F.69 code is: 72, if the “national call number” is 5 digits long. 720, if the “national call number” is less or more

10、than 5 digits.Note 7 Are there one or two printable letters following the “national call number”, and is there no further printablecharacter following? One space between “national call number” and network identification code is allowed.Note 8 Are there one or two printable letters preceding immediately the “national call number” (without spacebetween), but with a space in front of the letter(s).Note 9 If unsuccessful, perform one retry after 1.5 seconds, if allowed in the protocol.Note 10 If answerback is not received automatically.