<xsl:for-each-group select="Item" group-by="concat(Prefix, CatalogNumber, Range)">
<fo:block xsl:use-attribute-sets="base">
<xsl:for-each select="current-group()">

<!-- What do I put here so that I only get one copy of the Catalog Number?
(This code seems to go into an endless loop.)
-->
<xsl:apply-templates select="CatalogNumber" mode="do"/>

<xsl:apply-templates select="Title" mode="do"/>

               </xsl:for-each>
           </fo:block>
       </xsl:for-each-group>

	Martin Honnen
	http://msmvps.com/blogs/martin_honnen/