Definition on relationships in XML config

[Stefan Helmert]

Hello,

where can I find a formal definition of the relationships in the XML 
config files?

example:

In attribute-resolver.xml we have AttributeResolver (with the schema 
definition shibboleth-attribute-resolver.xsd) containing 
AttributeDefinition entries with "id" parameters.

In attribute-filter.xml we have AttributeFilterPolicyGroup (with the 
schema definition shibboleth-afp.xsd) containing many AttributeRule 
entries in AttributeFilterPolicy. The AttributeRule references the 
corresponding AttributeDefinition using the parameter "attributeID" 
which matches the "id" of AttributeDefinition.

I couldn't find this relationship definition in the both xsd files. 
Where are all theses relationships defined? Is this only done by the 
java code?

To have a formal description of the relationships would help to 
implement configuration checker/verifier to find missing links, 
anomalies etc.

Best regards

Stefan Helmert