sort problem

I've run into a sort problem with MSXML4 and wonder if it's a bug in that
processor or expected behavior. Basically, the problem seems to be related
to a sort where the select starts at the document node. See stylesheet and
sample XML below.

The stylesheet (sortTest.xsl):
==============================
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
        <xsl:template match="/">
                <xsl:value-of select="'&#x0A;'"/>
                <xsl:apply-templates select="test/content/listgroup"/>
        </xsl:template>
        <xsl:template match="listgroup">
                <xsl:apply-templates select="list">
                        <!-- the next sort statement is supposed to sort by 
@pos, but has no
effect in MSXML4. It does work as expected in MSXML3, Xalan 1.4 and Saxon
6.5 -->
                        <xsl:sort 
select="/test/data/list[(_at_)ref=current()/@id]/@pos"/>
                </xsl:apply-templates>
        </xsl:template>
        <xsl:template match="list">
                <xsl:value-of select="@id"/> - <xsl:value-of
select="/test/data/list[(_at_)ref=current()/@id]/@pos"/> - <xsl:value-of
select="."/>
                <xsl:value-of select="'&#x0A;'"/>
        </xsl:template>
</xsl:stylesheet>


The source XML:
===============
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="sortTest.xsl"?>
<test>
        <content>
                <!-- this is a static pre-defined content section, with list 
elements that
can be re-ordered by user/session preferences. -->
                <listgroup>
                        <list id="a" name="first">first list in content 
section</list>
                        <list id="b" name="second">second list in content 
section</list>
                        <list id="c" name="third">third list in content 
section</list>
                        <list id="d" name="fourth">fourth list in content 
section</list>
                </listgroup>
        </content>
        <data>
                <!-- this is a session-specific section (appended by an 
aggregation step
after page request) which contains the desired order of list elements in the
above content section. -->
                <list ref="a" pos="3"/>
                <list ref="b" pos="4"/>
                <list ref="c" pos="2"/>
                <list ref="d" pos="1"/>
        </data>
</test>

Expected output:
================
d - 1 - fourth list in content section
c - 2 - third list in content section
a - 3 - first list in content section
b - 4 - second list in content section

Output in MXSML4:
=================
a - 3 - first list in content section
b - 4 - second list in content section
c - 2 - third list in content section
d - 1 - fourth list in content section


In MSXML4 I get the output in document order, in stead of my
desired/expected output. I rewrote the sort select using keys but got the
same result.

I tested in MSXML3, Xalan 1.4 and Saxon 6.5, which gave the desired result.
Did I run into an MSXML4 bug or did the older processors not implement the
XSLT spec correctly? From reading the spec I don't see why my expected
result would not be allowed so I suspect a bug in MSXML4. Can anybody
confirm? Does anyone have a suggestion for a workaround?

Thanks,
Edward


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