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Re: Extension and all-group

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 03 Feb 2003 11:36:44 +0000
To: "Dare Obasanjo" <dareo@microsoft.com>
Cc: "Oleg Tkachenko" <olegt@multiconn.com>, <xmlschema-dev@w3.org>
Message-ID: <f5b4r7legtv.fsf@erasmus.inf.ed.ac.uk>

"Dare Obasanjo" <dareo@microsoft.com> writes:

> I know this rule exists but for the life of me can't find what parts
> of the REC spell it out. Can you give me a hand and provide a link
> or excerpt from the REC to back this up. We constantly get questions
> about this from our users and I'd like to point them to the REC to
> confirm my answers.

It's Schema Component Constraint: All Group Limited [1]:

  When a model group has {compositor} all all of the following must be
   1 one of the following must be true:
     1.1 It appears as the model group of a model group definition.
     1.2 It appears in a particle with {min occurs}={max occurs}=1,
         and that particle must be part of a pair which constitutes the
         {content type} of a complex type definition.
   2 The {max occurs} of all the particles in the {particles} of the
     group must be 0 or 1.

This is not as clear as it might be, and has been re-worded in a
forthcoming erratum, but the substance is unchanged.

Note this is a _component_ constraint, which is why the _component_
corresponding to the original example is broken, since it consists of
two 'all' groups in a sequence.


[1] http://www.w3.org/TR/xmlschema-1/#cos-all-limited
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                      Half-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 Monday, 3 February 2003 06:36:41 UTC

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