Re: Restrictions on existence of attributes?
> Howard Bartel wrote: >> On Jun 27, 2006, at 07:57, Rick Jelliffe wrote: >> How do I specify that an element MUST have ONLY ONE of a set of >> possible >> attributes? >> I understand that there is a "choice" option but it seems that >> this only >> applies to elements, not attributes within an element. > If you are using XML Schemas, then look at the "enumeration" > "facet" of "datatypes". Your element must be a "complex type". I don't think that'll solve Howard's problem since he wants only one of a set of attributes, not only one of a set of attribute values. Presumably this can always be remodelled with some indirection (e.g. having a @name attribute which is an enumeration, and an @value which would give its value), but that might not be an option. My XML Schema is getting very rusty since I don't get to use it much anymore, but I don't think it can be done (or if it can it involves dark magic). In RelaxNG it's just a <choice> of <attribute> elements, easy as ¹. -- Robin Berjon Senior Research Scientist Expway, http://expway.com/
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