SDL-News: SDL Keywords, Lexical rules

Subject: SDL-News: SDL Keywords, Lexical rules
Date: Thu Apr 24 1997 - 16:25:00 GMT

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-----From Rick Reed TSE <> to sdlnews -----

I have received a personal communication complaining that the keywords for

SDL (such as call, connect and error etc.) are names that are frequently

needed the SDL definition itself - especially when this is for telecomms.

For example, in draft Recommendation Q.1228, INAP for IN Capability Set

2, connect and error are legitimate signals. In the SDLs of Annex

A/Q.1228 they have been spelt 'errror' and 'connnect" to avoid

problems! This then makes importation of the associated ASN.1 from the

parent Recommendation messy, to say the least.

Also the lexical rules of Z.100 are not completely implemented in some

tools, which inhibits the portability of both SDL/GR and SDL/PR even with


Moreover, there are problems interfacing SDL with other languages (at lower

and higher levels) where these are case sensitive or have different rules

for identifiers.

Lastly, in in Z.100 and in other publications on SDL, the keywords are

often distinguished by a different font (usually bold).

Given this background, I suggest that the lexical rules for SDL are

reconsidered. However, there MUST be some compatibility provided (in some

way) with existing SDL that is machine readable.

There are obviously many possible approaches (such as visually distinct

fonts for keywords), but before refining the requirements and strating the

study, the level of user support should be established.

More views please.


Rick Reed, TSE Limited

13 Weston House, 18-22 Church Street

Lutterworth Leicestershire LE17 4AW United Kingdom

Tel +44 14 55 55 96 55; Fax +44 14 55 55 96 58


-----End text from Rick Reed TSE <> to sdlnews -----

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