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Re: complexType : extension of a sequence by a choice ?

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Tue, 10 Feb 2004 09:39:23 +0000
To: noah_mendelsohn@us.ibm.com
Cc: "'Bruno Chatel'" <bcha@chadocs.net>, "Michael Kay" <mhk@mhk.me.uk>, xmlschema-dev@w3.org
Message-ID: <f5bu11z5l4k.fsf@erasmus.inf.ed.ac.uk>

noah_mendelsohn@us.ibm.com writes:

<snip/>

> Again, I'm not making a strong push that we add extension for all groups: 
> I'm merely suggesting that I think we could do so in a coherent and useful 
> way if there proved to be demand from users.  I believe that the rules for 
> extension (and restriction) could parallel those for attributes.   Maybe 
> I'm missing something.

The attribute parallel is interesting and (nearly) compelling.  I'm
still a little nervous about a conditional invariant -- that is, on
your proposal the V1 application would have to be _much_ smarter --
instead of depending on one invariant across the board, without appeal
to type information, it would have to know in some detail what the
types of the nodes it was processing were.  In practice I fear this
might mean the difference between a viable versioning story and one
which would be dismissed as too complex.

ht
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
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Received on Tuesday, 10 February 2004 04:39:56 GMT

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