- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 27 Mar 2003 14:11:15 +0000
- To: Wendy Attenberger <Wendy.Attenberger@nreis.com>
- Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
Wendy Attenberger <Wendy.Attenberger@nreis.com> writes:
> <Alphabet>
> <A>
> <B>
> <C>
> </Alphabet>
> In the schema, how do you indicate that at least one item is required (A,B
> or C), but also allow for some ("A and B" OR "B and C", etc.) items or all
> items(A,B, & C) to be present in the xml?
> We've messed around with the <xs:choice>, <xs:all> ,minOccurs and maxOccurs,
> but we can't get the right combination? Any ideas? Thanks.
Funny you should ask -- the XML Schema Working Group is looking at
possible additions to the language for version 1.1 which would
provide for this in a simple way. As it stands the only way is by
a massive content model, illustrated here for the 3 element case:
((a , ((b , c?) | (c , b?))) |
(b , ((a , c?) | (c , a?))) |
(c , ((b , a?) | (a , b?))))
Needless to say, this would be pretty large for the 26 element case.
ht
--
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@cogsci.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 Thursday, 27 March 2003 09:11:16 UTC