[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Best Practice for this problem?
Paul Spencer <paul.spencer@b...> writes: > I have recently been asked to look at a schema, of which this is a part: <snip/> > The intention is clear - at least one of the three elements <Town>, > <Locality>, <County>, but each must not appear more than once. There are several problems here -- first of all, you are breaking the unique attribution rule. Second of all, you haven't got all the bases covered. The DTD equivalent of what you want is ((t,((c,d?)|(d,c?))?)|(c,((t,d?)|(d,t?))?)|(d,((c,t?)|(t,c?))?)) Just transcribe this into XML Schema. > I believe the format to be non-compliant with XML Schema since each of the > three elements has multiple definitions within the same scope. XML Authority > 2.1 agrees with me, XML Spy 3.5 does not. Nope, they all have the same type, so that's OK. > If I am right, there are two choices: > > 1. Define the three elements globally, then reference them as required. This > loses the benefit of a local definition within the complex data type. You could certainly do that. > 2. Define the elements as at the start of the example: > > <xsd:choice> > <xsd:element name="Town" type="bs7666:TownType"/> > <xsd:element name="Locality" type="bs7666:LocalityType"/> > <xsd:element name="County" type="bs7666:CountyType"/> > </xsd:choice> > > Then access by reference from there. For example: > > <xsd:sequence> > <xsd:element ref="Town"/> > <xsd:element ref="Locality"/> > </xsd:sequence> > > I have never seen an example that uses "ref=" pointing to a locally scoped > definition. Is this allowed? Not allowed, although we considered it and may come back to it. 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@c... URL: http://www.ltg.ed.ac.uk/~ht/
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