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Re: Parametric minOccurs, maxOccurs?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 15 Mar 2000 09:55:03 +0000
To: "Eric Rehm" <rehm@singingfish.com>
Cc: <www-xml-schema-comments@w3c.org>
Message-ID: <f5b66uo4ky0.fsf@cogsci.ed.ac.uk>
"Eric Rehm" <rehm@singingfish.com> writes:

> I'd like to restrict the number of elements in a <sequence> by an attribute,
> e.g.,
> 
> <!-- desired, but not currently valid, XML Schema -->
> 
> <complexType name="VectorI">
>     <attribute name="Size" type="integer"/>
>     <sequence minOccurs="Size" maxOccurs="Size"> 
>         <element name="ValueVectorI" type="integer"/>
>     </sequence>
>  </complexType>
> 
> This seems like it would be a pretty common schema feature.  Is
> there a way to do this?

Two classes of co-constraints were considered by the WG for XML Schema
but postponed for a later version:

  co-occurrence constraints among the attributes and children of an
  element, e.g. "this attribute XOR that attribute";

  instance-parameterised constraints (you need one such to provide a
  strict schema for an XSLT stylesheet).

Your requirement falls in to the latter category.  We hope to provide
for it, but not in v.1.

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 Wednesday, 15 March 2000 04:55:06 GMT

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