W3C Schema substitution-group question

I'm using a substitution group of 2 element types. The head element
and the alternative element are in different namespaces.

In my XML document, I'm instantiating the alternative element
where the schema mandates the head should go. If I import the
2nd namespace in the schema, everything works.

But why should I import the 2nd namespace in the schema
if nothing in the schema refers to it? I want the dependencies to
be one-way. I'd prefer to get this 2nd namespace with the
schemaLocation attribute in the document, because the
document DOES depend on it.

But when I try to do so, the processor does not even read my
2nd namespace's schema as specified in schemaLocation. It
reads the original schema and tells me I have invalid content.

It seems as if the processor wants all schemas referenced
by schemaLocation to be complete in and of themselves, ignoring
possible inheritance across them. Maybe this is the correct behaviour,
but I don't know.

I'm using Java and JWSDP1.0_01


					David