Hi David,

Thanks for your response. The solution using xsl:key seems to be the
most elegant, however the xml data I am working with comes from two
external xml files, one containing

<Packages>
    <Package>
      <PkgBenefitCode>1</PkgBenefitCode>
      <PkgBenefitCode>2</PkgBenefitCode>
      <PkgBenefitCode>3</PkgBenefitCode>
    </Package>
  ...
</Packages>

and the other containing

<Benefits>
    <Benefit code="1">
      <Content>The content 1</Content>
    </Benefit>
    <Benefit code="2">
      <Link>http://www.example.com</Link>
    </Benefit>
    <Benefit code="3">
      <Content>The content 3</Content>
    </Benefit>
    ...
</Benefits>

It is not possible to reference an external document with a key, except
when the context is changed (See http://www.w3.org/TR/xslt#key). I
could change the context to the document containing the key but this
wouldn't solve my problem of needing to reference the other document.

I will try one of the other solutions but I wonder if there is any way
of using a key or similar across documents in this fashion?

Thanks again for your help.
Dirk