[sc34wg3] TMCL Declarations vs. Global Validation Rules

Patrick Durusau patrick at durusau.net
Fri Jun 19 14:39:28 EDT 2009


This is one of those "other" comments. ;-)

6.1 General says:

> TMCL provides a number of constructs known as declarations, which 
> allow Topic Maps constructs to be used in ways which would otherwise 
> be forbidden by the global validation rules. Declarations are in a 
> sense the opposite of constraints, in that their effect is to relax 
> constraints built into TMCL. 
OK, but then I look at 6.3 Name Type, for example and its declaration 
appears to be:

> Making a topic an instance of |tmcl:name-type| is a declaration that 
> the topic may be used as a name type. 
With a global validation rule that follows an example that says:

> *Global Validation Rule:* any topic name item /n/ whose |[type]| 
> property contains a topic item /t/ where /t/ is not an instance of 
> |tmcl:name-type| is invalid. 
It looks like the "global validation rule" is a mirror of the declaration.

Question: Why do we need declarations plus "global validation rules?"

Understanding that we need global rules but not understanding why we 
can't simply state them? What do we gain by having a separate "declaration?"

BTW, thanks to the editors for the latest draft!


Patrick Durusau
patrick at durusau.net
Chair, V1 - US TAG to JTC 1/SC 34
Convener, JTC 1/SC 34/WG 3 (Topic Maps)
Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)

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