We need to add <a name="some_name">title</a>
around each composition title so we have something to link to.
The generate-id() function will choose a unique ID
for a particular element.
Here's the new template for the composition
<xsl:template match="composition">
<h3>
<a name="{generate-id()}">
<xsl:value-of select="title"/>
</a>
</h3>
<ul>
<xsl:if test="string(date)">
<li><xsl:value-of select="date"/></li>
</xsl:if>
<xsl:if test="string(length)">
<li><xsl:value-of select="length"/></li>
</xsl:if>
<xsl:if test="string(instruments)">
<li><xsl:value-of select="instruments"/></li>
</xsl:if>
<xsl:if test="string(publisher)">
<li><xsl:value-of select="publisher"/></li>
</xsl:if>
</ul>
<p><xsl:apply-templates select="description"/></p>
</xsl:template>
Here's the new template for the table of contents link
<xsl:template match="catalog">
<head>
<title><xsl:value-of select="category"/></title>
</head>
<body>
<!-- Header -->
<h1><xsl:value-of select="category"/></h1>
<ul>
<xsl:for-each select="composition">
<xsl:sort select="title"/>
<li>
<a href="#{generate-id()}">
<xsl:value-of select="title"/>
</a>
</li>
</xsl:for-each>
</ul>
<!-- Body -->
<xsl:apply-templates select="composer">
<xsl:sort select="name/last_name"/>
<xsl:sort select="name/first_name"/>
<xsl:sort select="name/middle_name"/>
</xsl:apply-templates>
<!-- Signature -->
<hr/>
Copyright <xsl:value-of select="copyright"/><br/>
Last Modified: <xsl:value-of select="last_updated"/><br/>
<xsl:apply-templates select="maintainer"/>
</body>
</xsl:template>
Although the ID is generated in two separate places, it is generated for the same node. Consequently, they are the same.