Re: keyrefs

Hi Jeni,

Jeni Tennison wrote:

> 
> Yes. My feeling is that when you design a markup language, you should
> pay more attention to the ease with which documents in that markup
> language can be created and processed than to whether the constraints
> that you want to express can be expressed in a particular schema
> language. If a validatable structure is a big requirement for the
> markup language, then great, try to make it fit in with the schema
> language you've chosen, but if not, the main role of a schema is
> documentation and often natural language is as good a definition
> language as anything.


I does more than agree and I would say that, even if "a validatable 
structure is a big requirement for the markup language" you may consider 
  defining a flexible vocabulary and a (strict) canonical form which can 
be validated by any schema language (including W3C XML Schema and even 
DTDs).

You can of course also publish the canonicalization process as a XSLT 
transformation to be perfomed on instance documents before validation.

The only caveat for this is that the chain (transformation / validation) 
is not natively supported by XML tools such as editors, but otherwise I 
think that it's a great way to abstract your vocabulary from schema 
technologies.

 
> The reason Schematron is so useful is that while other languages are
> limited in their grammar, 


Except Examplotron ;=) ... but I have to admit I have borrowed the idea 
and the ending of the name from Schematron.

> XPath expressions are able to articulate
> quite a lot of the rules that natural language can articulate about
> XML structures. But there are some aspects of validation that just
> aren't testable without a semantic understanding of the role of the
> XML document.


My 0,02 Euros.

Eric
-- 
Rendez-vous à Paris pour le Forum XML.
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
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Received on Friday, 9 November 2001 12:55:04 UTC