Many Key values question

Hi,



Here is my XML



<collection>

  <record>

    <datafield tag="773" ind1="0" ind2=" ">

 <subfield code="5">BULLETIN / EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH
</subfield>

 <subfield code="t">Bulletin / Eidgenvssische Technische Hochschule Z|rich
</subfield>

 <subfield code="d">Z|rich : Schulleitung der ETH Z|rich, 1993-2005
</subfield>

 <subfield code="g">S. 27-33</subfield>

 </datafield>

  </record>

</collection>



I want to index in the same key

subfield[@code=5] and subfield[@code=t]



Ive tried this :
<xsl:key name="idxrev" match="datafield[@tag=773]"
use="concat(subfield[@code='5'],subfield[@code='t'])"/>



To display the keys, I use this :


<xsl:for-each select="record/datafield[@tag=773]">

            <xsl:sort select="
concat(subfield[@code='5'],subfield[@code='t'])"/>

            <xsl:value-of select="key('idxrev',
concat(subfield[@code='5'],subfield[@code='t']))"/>

            <br/>

</xsl:for-each>



But all the subfields are in the key not only the subfields 5 and t.



Returned key :

BULLETIN / EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH Bulletin /
Eidgenvssische Technische Hochschule Z|rich Z|rich : Schulleitung der ETH
Z|rich, 1993-2005 S. 27-33



Thx
JP