Is there a way to specify that one of 2 attributes is required in XSD?
for example, I have a definition like this:
<xs:attribute name="Name" type="xs:string" use="optional" />
<xs:attribute name="Id" type="xs:string" use="optional" />
I want to be able to define that at least one of these is required. Is that possible?
No, I don't think you can do that with attributes. You could wrap two <xs:element> into a <xs:choice> - but for attributes, there's no equivalent construct, I'm afraid.
Marc is quite right... You cannot have xs:attribute child elements inside a xs:choice parent element in XSD.
The logic seems to be that if two instances of an element have a mutually exclusive set of attributes then they are logically two different elements.
A workaround for this has been presented by Jeni Tennison here.