XLink help

I’m trying to understand how best to implement xlink in the context of the following scenario.

I have a schema, say root.xsd, which describes:

<Root>

            <A>

                        <B maxoccurs=”unbounded”>

                                    <xs:element ref=”X”/>

                                                …

                        </B>

            </A>

</Root>

<X>Global type definition of ‘X’</X>

The objective is to support the definition of instance documents that only define instances of <X> that can

be aggregated, and referenced by <B>, into a single “master” instance document.  Thus, I would have

root.xml and n instances of xdef_n.xml that need to be linked.

From the Xlink specification I am under the impression that I could create an extended link to contain

the links between root.xml and the instances of xdef_n.xml.  However, I am unsure as to what needs to

be defined, if anything, within root.xsd.

Thanks in advance.