Given the document:

<vendors>
<vendor><name>Dell</name>...</vendor>
<vendor><name>Apple</name>...</vendor>
<vendor><name>HP</name>...</vendor>
</vendors>

This would sort the vendor elements:

<xsl:template match="vendors">
<xsl:copy>
<xsl:apply-templates select="vendor">
<xsl:sort select="name"/>
</xsl:apply-templates>
</xsl:copy>
</xsl:template>

<xsl:template match="vendor">
<xsl:copy-of select="."/>
</xsl:template>