<xsl:for-each select="id(@ref)/@references">
   <xsl:value-of select="."/>
 </xsl:for-each>

 <xsl:for-each select="id(id(@ref)/@references)">
   <xsl:value-of select="."/>
 </xsl:for-each>

thanks
..dan

<!DOCTYPE x [
<!ATTLIST y id ID #IMPLIED>
]>
<x ref=" e c a a ">
  <y id="a">1</y>
  <y id="b">2</y>
  <y id="c">3</y>
  <y id="e">4</y>
</x>

<xsl:stylesheet version="1.0"
              xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="x">
 <xsl:for-each select="id(@ref)">
   [<xsl:value-of select="."/>]
 </xsl:for-each>
</xsl:template>

</xsl:stylesheet>

$ saxon idref.xml idref.xsl
<?xml version="1.0" encoding="utf-8"?>
   [1]

[3]

[4]

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---------------------------------------------------------------------------
Danny Vint

Specializing in Panoramic Images of California and the West
http://www.dvint.com

When H.H. Bennett was asked why he preferred to be out
shooting landscapes rather than spending time in his portrait studio: