passing variable through to document() call.

I have a parent document with code like:
<doc>
<render2web/> <!-- this sets the variable -->
<lookup about="consumer"/>
</doc>

And in the xsl:
<xsl:apply-templates 
select="document('/home/eric/lookup.xml')/doc/topic[(_at_)about=$about]"/>

Problem is that when applying the templates in this call above, the variable set
in the xml above is not seen.

How do I implement this - tried and failed to implement with a call-template.

Thanks a lot.

-- 
Eric Smith

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