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Re: [xml-dev] 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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