RE: [xml-dev] XML schema -- specify a relationship between attributes?

["Chiusano Joseph" <chiusano_joseph@bah.com>]

W3C Schema does not have the capability to satisy your requirement -
which is commonly known as a "co-occurrence constraint" requirement.
Your next options would be to consider using Schematron, or to use
programmatic means for this validation.

Kind Regards,
Joseph Chiusano
Booz Allen Hamilton
Strategy and Technology Consultants to the World
 

> -----Original Message-----
> From: Stewart Johnson [mailto:stew@fatcaterpillar.org] 
> Sent: Monday, November 22, 2004 2:55 PM
> To: xml-dev@lists.xml.org
> Subject: [xml-dev] XML schema -- specify a relationship 
> between attributes?
> 
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> Hash: SHA1
> 
> Hey All -
> 
> I hope this is an appropriate place for this question.
> 
> I'm stuck while trying to write a schema, hoping someone can 
> provide me with a flash of inspiration.
> 
> One of the elements I'm specifying has two attributes, both 
> of which are optional. I want to express in the schema that 
> there's a relationship between the two -- that the second 
> attribute is optional only if the first one is not specified. ie:
> 
> <myElement /> <!-- valid -->
> <myElement name="A" /> <!-- valid -->
> <myElement myattr="true" /> <!-- invalid because name isn't 
> specified --> <myElement myattr="true" name="A" /> <!-- valid -->
> 
> So far my schema looks like this:
> 
> <element name="myElement">
> 	<complexType>
> 		<attribute name="name" type="string" use="optional" />
> 		<attribute name="myattr" type="boolean" 
> use="optional" default="false" />
> 	</complexType>
> </element>
> 
> That captures the default values and the optional nature of 
> the two elements, but it doesn't capture the relationship 
> between the two. Is there any xsd construct I can use to 
> express the relationship? I know how to do it with elements 
> (xsd:group, xsd:choice) but not with attributes.
> 
> Thanks for any thoughts.
> 
> Stewart
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