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Content model of <complexType>

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 12 May 2000 10:21:11 +0100
To: www-xml-schema-comments@w3.org
Message-ID: <f5bwvl0i0oo.fsf@cogsci.ed.ac.uk>
Currently this is as follows:

   <sequence>
    <choice>
     <element ref="facet" minOccurs="0" maxOccurs="unbounded"/>
     <group ref="particle" minOccurs="0" maxOccurs="unbounded"/>
    </choice>
    <group ref="attrDecls"/>
   </sequence>

where 'particle' is

  <group name="particle">
   <choice>
   <element name="element" type="localElement"/>
   <element name="group" type="groupRef"/>
   <element ref="all"/>
   <element ref="choice"/>
   <element ref="sequence"/>
   <element ref="any"/>
   </choice>
  </group>

I'd like to change this to

   <sequence>
    <choice>
     <element ref="facet" minOccurs="0" maxOccurs="unbounded"/>
     <group ref="explicitGroup"/>
    </choice>
    <group ref="attrDecls"/>
   </sequence>

where 'explicitGroup' is

  <group name="explicitGroup">
   <choice>
   <element name="group" type="groupRef"/>
   <element ref="all"/>
   <element ref="choice"/>
   <element ref="sequence"/>
   </choice>
  </group>


I think the defaulting of the wrapper is messy, confusing and is
getting in our way: the increased clarity in requiring a single <all>,
<choice> or <sequence> outweighs the extra verbosity.

The one potential problem is that people will have to learn to write e.g.

  <complexType name="paraContent" content="mixed">
   <choice minOccurs="0" maxOccurs="1">
    <element ref="emph"/>
    <element ref="strong"/>
     . . .
    </choice>
   </complexType>

for backward-compatible mixed content.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, 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/
Received on Friday, 12 May 2000 05:21:14 UTC

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