Questions on sorting

Hi all,

I'm a bit confused by the interaction of xsl:sort and the various
axes.  I suppose basically my question is: does xsl:sort affect the
ordering of nodes for the purpose of reference within the stylesheet,
or just for the purpose of the output?

To try to get a grip on this, I took this XML

<?xml version="1.0"?>
<root>

<foo>D</foo>
<foo>C</foo>
<foo>A</foo>
<foo>B</foo>

</root>

and this stylesheet

<?xml version='1.0'?>
<xsl:stylesheet
    xmlns:xsl="http://www.w3.org/XSL/Transform/1.0"
    indent-result="yes">

<!-- The root of the document -->
<xsl:template match="/">
  <xsl:for-each select="//foo">
    <xsl:sort/>
    <xsl:value-of select="."/>:<xsl:for-each select="preceding-sibling">
      <xsl:value-of select="."/>
    </xsl:for-each>/<xsl:for-each select="following-sibling">
      <xsl:value-of select="."/>
    </xsl:for-each>
    <xsl:text>
</xsl:text>
  </xsl:for-each>
</xsl:template>

</xsl:stylesheet>

And I obviously don't understand preceding-sibling, because the
output (using the latest XT) was

A:/
B:/
C:/
D:/

So two questions:
1) When processing C what are:

preceding-sibling (A+B or D)?
following-sibling (D or A+B)?

and would this change if the xsl:sort came after the
xsl:apply-templates?

2) Why doesn't

<xsl:for-each select="preceding-sibling">
  <xsl:value-of select="."/>
</xsl:for-each>

print anything out?

Thanks,

Ian
--
Ian Brockbank, Indigo Active Vision Systems, The Edinburgh Technopole,
Bush Loan, Edinburgh EH26 0PJ   Tel: 0131-475-7234  Fax: 0131-475-7201
work: ian@xxxxxxxxxxxxxx           personal: Ian.Brockbank@xxxxxxxxxxx
web: ScottishDance@xxxxxxxxxxx           http://www.scottishdance.net/


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