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Re: all groups: top level only?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 08 Dec 2002 21:46:50 +0000
To: "Morris Matsa" <mmatsa@us.ibm.com>
Cc: xmlschema-dev@w3.org
Message-ID: <f5bu1honpyt.fsf@erasmus.inf.ed.ac.uk>

"Morris Matsa" <mmatsa@us.ibm.com> writes:

> We had the impression that all groups can only occur at the top level of a
> content model.  This appears to be incorrect.  I'd like to ask about two
> cases.
> 
> [BTW - Thanks to Henry for his last answer.]
> 
> Case 1.  Extending an all group with another element in sequence after it.
> We believe that we read the spec as saying that this is illegal by clause 1
> of [1]

That's correct.

> Indeed, SQC says that it is bad for exactly that reason.  However,

Good.

> XSV says that it is a legal schema.

Bad.  XSV bug, thanks.

> Case 2.  This time much the same content model is produced (All(a,b,c), d),
> but with an xsd:group, which the spec seems to allow via clause 1.1 of [1]
> (at least we're not sure how else to understand that.)  Indeed, both XSV
> and SQC permit it.

There's a clarification coming to try to make it clear that since the
referenced clause is about components, it doesn't matter how you get
there, it's bad.  So (once that erratum is published) XSV and SQC will
both need to change.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Sunday, 8 December 2002 16:46:48 GMT

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