Putting <xref> inside <type>

I'm documenting an object-oriented class structure, and would like to 
use cross-references whenever possible, mainly to save me from 
copy-and-pasting everything, but also so the rendered output is 
clickable.  However, when I describe a method with:

<methodsynopsis>
    <type><xref linkend="part2.Array"/></type>
    <methodname>Array</methodname>
    <methodparam choice="opt" rep="repeat">
        <parameter>item</parameter>
    </methodparam>
</methodsynopsis>

my validating parser complains about the <xref/> element.  Is there a 
reason why I can't put a cross-reference inside a <type>?  If  I can't 
do this, is there some other way I can accomplish something similar?