Fantastic -- exactly what I was looking for, straightforward and simple.
Will try this out tonight.  Thanks!

Michele

-----Original Message-----
From: Martin Honnen martin.honnen@xxxxxx
[mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx]
Sent: Tuesday, April 14, 2015 12:39 PM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re:  Sorting things on two levels

Michele R Combs mrrothen@xxxxxxx wrote:

>> Looks like grouping and sorting to me. Do you use XSLT 1.0 or 2.0?
>
>
> I'll be running the transform using the latest version of Oxygen, so it
looks like either would be fine.  From the Oxygen Help file:

With XSLT 2.0 here is an approach:

<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:xs="http://www.w3.org/2001/XMLSchema"
   exclude-result-prefixes="xs">

<xsl:output method="html" indent="yes"/>

<xsl:template match="root">
   <ul>
     <xsl:for-each-group select="indexterm" group-by="primary">
       <xsl:sort select="current-grouping-key()"/>
       <li>
         <xsl:value-of select="current-grouping-key(), if
(not(current-group()/secondary)) then current-group()/@id else ()"
separator=", "/>
         <xsl:if test="current-group()/secondary">
           <ul>
             <xsl:for-each-group select="current-group()"
group-by="secondary">
               <xsl:sort select="current-grouping-key()"/>
               <li>
                 <xsl:value-of select="current-grouping-key(),
current-group()/@id" separator=", "/>
               </li>
             </xsl:for-each-group>
           </ul>
         </xsl:if>
       </li>
     </xsl:for-each-group>
   </ul>
</xsl:template>

</xsl:stylesheet>

Outputs

<ul>
    <li>aardvarks, {ID}</li>
    <li>bears
       <ul>
          <li>breeding, {ID}</li>
          <li>feeding, {ID}</li>
          <li>hunting, {ID}, {ID}</li>
       </ul>
    </li>
</ul>

for your sample data.