I would to create a list of references (like an element of IDREFS type) using key and keyref, so that each item in my list (Links in the example below) refers the attribute @name of a Link.
The code below do not works, but I would to write something like that:
<xs:element name="root">
<xs:complexType>
<xs:sequence>
<xs:element name="Node">
<xs:complexType>
<xs:sequence>
<xs:element name="Links">
<xs:simpleType>
<xs:list itemType="xs:string" />
</xs:simpleType>
<xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Link">
<xs:complexType>
<xs:attribute type="xs:string" name="name" use="required" />
<xs:attribute type="xs:string" name="source" use="required" />
<xs:attribute type="xs:string" name="destination" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:key name="LinkKey">
<xs:selector xpath="Link" />
<xs:field xpath="@name" />
</xs:key>
<xs:keyref name="LinkRef" refer="LinkKey">
<xs:selector xpath="Node" />
<xs:field xpath="Links" />
</xs:keyref>
<xs:element>
instead of:
<xs:element name="root">
<xs:complexType>
<xs:sequence>
<xs:element name="Node">
<xs:complexType>
<xs:sequence>
<xs:element name="Links" type:"xs:IDREFS" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Link">
<xs:complexType>
<xs:attribute type="xs:ID" name="name" use="required" />
<xs:attribute type="xs:string" name="source" use="required" />
<xs:attribute type="xs:string" name="destination" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:element>
Is it possible?
No, this isn't possible using key and keyref. You would need to use XSD 1.1 assertions.