Dear XSLT list,

Is there an easy way in XPath (not using XSLT instructions) to select only the first occurrence of a specific value in a sequence of atomic values, so as to return the sequence in the original order, but with re-occurrences of each value after the first appearance of that value removed? For example, given an input sequence:

('Matthew','Mark','Luke','Matthew','John')

I want to produce

('Matthew','Mark','Luke','John')

I can't rely on using distinct-values() because that isn't guaranteed to keep specifically the *first* occurrence of a value.

In an XSLT context I can construct a temporary tree, poke each value into an element, all on the same level in the hierarchy, and then test for:

*[not(preceding-sibling::* = .)]

but I don't know how to write an XPath predicate that will filter the sequence of *atomic values* the way I want. Is this just a blind spot? Can anyone advise?

T:\ftemp>xslt2 david.xsl david.xsl
<?xml version="1.0" encoding="UTF-8"?>Matthew Mark Luke John
T:\ftemp>type david.xsl
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="2.0">

T:\ftemp>xslt2 david2.xsl david2.xsl
<?xml version="1.0" encoding="UTF-8"?>Matthew Mark Luke John
T:\ftemp>type david2.xsl
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="2.0">

</xsl:stylesheet>
T:\ftemp>

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