- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 24 Oct 2001 16:18:18 +0100
- To: sandygao@ca.ibm.com
- Cc: www-xml-schema-comments@w3.org
sandygao@ca.ibm.com writes: > >From constraint "Unique Particle Attribution" [1] and appendix H [2], I > couldn't figure out whether the following content model (<choice>) violates > UPA constraint: > > <group name="grp"> > <sequence> > <element name="e"/> > </sequence> > </group> > > <choice> > <group ref="grp"/> > <group ref="grp" maxOccurs="3"/> > </choice> > > In [1], it mentions "particle ... can be uniquely determined". But it's not > clear to me whether such "particle" refers only to "non-group particle" or > generic "particle". In the above example, there are two (different) group > particles, but they refer to the same non-group particle. When we see an > element "e" in the instance, we can uniquely determine the non-group > particle for validation, but not a unique group particle. The UPA applies to components, not representations, so particles _are_ the right thing to worry about. But the above is still in violation, because it corresponds to the same component that <choice> <sequence> <element name="e"/> </sequence> <sequence max='3'> <element name="e"/> </sequence> </choice> corresponds to. For the purposes of UPA, the sequences are themselves irrelevant, so we get <choice> <element name="e"/> <element name="e" maxOccurs="3"/> </choice> which clearly violates the UPA. > [1] http://www.w3.org/TR/xmlschema-1/#cos-nonambig > [2] http://www.w3.org/TR/xmlschema-1/#non-ambig 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, 24 October 2001 11:17:31 UTC