RE: Need test for preceding-sibling

Now I see that I over-simplified the problem. The XSLT also has to suppress any <a1> that is not paired with an <a2>.

So, I'm not sure the grouping works in your example since there could be two <a1/> elements that are in the group that ends with <a2/>. But, if you specify:

        <xsl:for-each-group select="*"
                                group-starting-with="a1"
                       group-ending-with="a2">

will that consider "<a1/><a1/><a2/>" a group?

T:\ftemp>type hintz.xml
<test>
<a1/>
<a2/>
<a1/>
<a2/>
<b/>
<c/>
<a2/>
<d/>
<a1/>
<e/>
<a1/>
<f/>
<a2/>
<g/>
</test>

T:\ftemp>xslt2 hintz.xml hintz.xsl
<?xml version="1.0" encoding="UTF-8"?>
<a1/>
<a2/>
<a1/>
<a2/>
<!--Missing paired a1-->
<b/>
<c/>
<a2/>
<d/>
<a1/>
<e/>
<!--Missing paired a2-->
<a1/>
<f/>
<a2/>
<g/>
T:\ftemp>type hintz.xsl
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="2.0">

<xsl:template match="test">
  <xsl:for-each-group select="*"
                      group-starting-with="a1">
    <xsl:for-each-group select="current-group()"
                        group-ending-with="a2">
      <xsl:choose>
        <xsl:when test="exists(current-group()/self::a1) =
                        exists(current-group()/self::a2)">
          <xsl:copy-of select="current-group()"/>
        </xsl:when>
        <xsl:when test="current-group()/self::a1">
          <xsl:copy-of select="current-group()"/>
          <xsl:comment>Missing paired a2</xsl:comment><xsl:text>
</xsl:text>
        </xsl:when>
        <xsl:otherwise>
          <xsl:comment>Missing paired a1</xsl:comment><xsl:text>
</xsl:text>
          <xsl:copy-of select="current-group()"/>
        </xsl:otherwise>
      </xsl:choose>
    </xsl:for-each-group>
  </xsl:for-each-group>
</xsl:template>

</xsl:stylesheet>
T:\ftemp>

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