> I would like to group adjacent siblings which share the same 
> local-name
> into a container element.
> 
> I thought that this would be the classical use-case for an
> <xsl:for-each-group> with @group-adjacent, but I am getting the
> strangest results...

I can't tell what you are doing wrong without seeing your code.

With ax as the context node, you can do

<xsl:for-each-group select="*" group-adjacent="local-name()">
  <xsl:choose>
    <xsl:when test="current-grouping-key()='ex'">
      <remark><xsl:copy-of select="current-group()"/></remark>
    </
    <xsl:otherwise>
      <xsl:copy-of select="current-group()"/>
    </
  </
</

Michael Kay
http://www.saxonica.com/