selection with multiple keys

I've found keys, defined with xsl:key and selected with the key() function
real useful. However I'm having problems selecting using multiple keys.
Defining the keys works fine. But I can only select them one at a time. When
I try
<xsl:apply-templates select="key('PrID', 'key1|key2')"/>
this doesn't work. Not too much a suprise as for this construct the
'key1|key2' should be converted to a string and there is no such key (though
both do exist individually).

Next I tried
<xsl:apply-templates select="key('PrID', 'key1')|key('PrID', 'key2')"/>
and suprisingly no nodesets are selected, even though both would be selected
on their own.

Finally I tried using a node set as the second argument to key(), as the
XSLT standards says
'When the second argument to the key function is of type node-set, then the
result is the union of the result of applying the key function to the string
value of each of the nodes in the argument node-set.'
However this sort of expression also returns nothing:
<xsl:apply-templates select="key('PrID', /document/ruleset/rule/@id)"/>

where in my xml I have:
<document>
...
<ruleset>
    <rule id="key1"/>
    <rule id="key2"/>
</ruleset>
</document>

Any gurus out there with any ideas as to what's going wrong?

I'm running xalan 19.0.2 and xerces 1.0.1, if that makes any difference.


Many thanks

Tim

--------------------------------------------
Dr. Tim Dudgeon, Bioinformatics group leader
British Biotech Pharmaceuticals
Watlington Road, Oxford, OX4 5LY, UK
Tel: (44) 1865 748747
Fax: (44) 1865 781034
email: dudgeon@xxxxxxxxxxxxx


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