- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 14 Mar 2002 17:23:59 +0000
- To: "Beyer,Nathan" <NBEYER@cerner.com>
- Cc: "Schema Dev XML (E-mail)" <xmlschema-dev@w3.org>
"Beyer,Nathan" <NBEYER@cerner.com> writes: > below... > > -----Original Message----- > From: ht@cogsci.ed.ac.uk [mailto:ht@cogsci.ed.ac.uk] > > > The second says > > choose (any number of times) between a required c1 or a required c2 > >So you're allowed nothing, or c1, or c2, or c1c1, or c1c2, or c2c1, > > or c2c2, or . . . > > The piece that's confusing is that c1 and c2 are required elements, yet I > could just have c1 and it would validate. Isn't c2 required? The way you > interpreted seems like you're just ignoring the occurs attributes of the > particles within the choice minOccurs='0' really does mean "0 or more". The choice takes precedent over what_ever_ is inside. Read "each time you make the choice, you are _required_ to chose between c1 and c2 -- but you can chose to make the choice 0 times. > >Perhaps converting to DTD notation would help? > > The first is (c1?|c2?) > > The second is (c1|c2)* > > Your earlier example was (c1*|c2*) > > I'm not extremely fluent in DTDs, but does (c1|c2)* allow for nothing? I > thought that was c1 or c2, one to many times. (c1|c2)* allows for nothing. (c1|c2)+ (== minOccurs='1') requires at least one. ht -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh W3C Fellow 1999--2002, 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/ [mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Thursday, 14 March 2002 12:24:01 UTC