Re: combining the children of similar nodes under one

Sounds like a grouping-problem...

Try something like:

<xsl:stylesheet ...>
<xsl:key name="prods-by-name" match="product" use="name" />
<xsl:key name="style-type-by-prod" match="style | type"
         use="concat(parent::product/name,.)" />

<xsl:variable name="distinct-prods"
  select="//product[generate-id(.)=generate-id(
    key('prods-by-name',name))]" />

<xsl:template match="root">
  <xsl:apply-templates select="$distinct-prods" mode="merge"/>
</xsl:template>

<xsl:template match="product" mode="merge">
<xsl:copy>
<xsl:copy-of select="name" />
<xsl:apply-templates select="key('prods-by-name',name)" mode="list" />
</xsl:copy>
</xsl:template>

<xsl:template match="product" mode="list">
<xsl:apply-templates select="(style | type)[generate-id(.)=generate-id(
key('style-type-by-prod',concat(
current()/name,.)))]" />
</xsl:template>

<xsl:template match="style | type">
  <xsl:copy-of select="." />
</xsl:template>

</xsl:stylesheet>