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Re: Range extension with redefine

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Fri, 30 Apr 2004 10:06:26 +0100
To: "Hirtle, David" <David.Hirtle@nrc-cnrc.gc.ca>
Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
Message-ID: <f5b8ygdesx9.fsf@erasmus.inf.ed.ac.uk>

"Hirtle, David" <David.Hirtle@nrc-cnrc.gc.ca> writes:

> A simple question: How does one "extend" a particle's occurrence range with
> <redefine>?  I am familiar with the specification's discussion of valid
> restrictions (http://www.w3.org/TR/xmlschema-1/#cd-model-restriction), but
> there seems to be no way to do the opposite of _extending_ an occurrence
> range.
> For example:
> one.xsd
> -------
> <xs:group name="some_group">
> 	<xs:sequence>
> 		<xs:element ref="a"/>
> 	</xs:sequence>
> </xs:group>

The following will achieve your goal, but it's clearly limited to
certain restricted cases:

<xs:redefine schemaLocation="one.xsd">
  <xs:group name="some_group">
      <xs:group ref="some_group"/>
      <xs:element ref="a" minOccurs="0" maxOccurs="unbounded"/>

This points towards a rather extreme design-for-change approach in
which _all_ element references in content models are replaced by
group references to single-element content models, so that you can
change any aspect of the model by a subsequent group redefinition.

 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@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Friday, 30 April 2004 05:07:30 UTC

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