- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 09 Mar 2001 16:42:12 +0000
- To: Ulrich Mehlhaus <Ulrich.Mehlhaus@ptv.de>
- Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
The traditional approach to this is ((a,b?)|b). If you allow either
order then it's ((a,b?)|(b,a?)). So in XML Schema syntax that's
<xs:choice>
<xs:sequence>
<xs:element ref="a"/>
<xs:element ref="b" minOccurs="0"/>
</xs:sequence>
<xs:element ref="b"/>
</xs:choice>
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, 9 March 2001 11:42:15 UTC