key based on items across several documents

Greetings all,

I am trying to create a key based on items across several documents.  Here
is a simplified version of what I'd like to do:

	<xsl:key name="ItemsWithName" match="$ItemFiles//item[@name]"
use="@name"/>

Creates a list of all <item>s that have an @name attribute, across several
documents (The ItemFiles variable gathers nodes across documents based on
input).  But it looks like I can't use variables in the match pattern part
of the key element.  I knew this was true in xslt 1.0, having wanted to do
this years ago, but also seems to be the case in xslt 2.0 as well.  Have I
been staring at this too long, or is there a way to do this that I'm not
thinking of in xslt 2.0?

Thanks in advance,
Paul Kiel