XSL array/hash/lookup table

The lookup file:

<?xml version="1.0"?>

<lookup>

<location id="1769" guide="TT00379a" average="TT123456"/>

<location id="1230" guide="TT003999" average="TT000001"/>

</lookup>

The code: NOTE: $id is a local variable:

<!-- look up the country guide ID -->

<xsl:variable name="guide">

<xsl:for-each select="document('lookup.xml')">

<xsl:value-of select="key('map',$id)/@guide"/>

</xsl:for-each>

</xsl:variable>