Mega Code Archive
If test=position() = 1 or zip!=preceding-sibling
<![CDATA[
File: Data.xml
<?xml version="1.0"?>
<addressbook>
<address>
<name>
<title>Mr.</title>
<first-name>Jack</first-name>
<last-name>Smith</last-name>
</name>
<street>1234 Main Street</street>
<city>New York</city>
<state>WI</state>
<zip>48392</zip>
</address>
</addressbook>
File: Transform.xslt
<?xml version="1.0"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" indent="no"/>
<xsl:template match="/">
<xsl:for-each select="addressbook/address">
<xsl:sort select="zip"/>
<xsl:if test="position() = 1 or zip!=preceding-sibling::address[1]/zip">
<xsl:text>
Zip code </xsl:text>
<xsl:value-of select="zip"/>
<xsl:text> (</xsl:text>
<xsl:value-of select="city"/>
<xsl:text>, </xsl:text>
<xsl:value-of select="state"/>
<xsl:text>): 
</xsl:text>
</xsl:if>
<xsl:if test="name/title">
<xsl:value-of select="name/title"/>
<xsl:text> </xsl:text>
</xsl:if>
<xsl:value-of select="name/first-name"/>
<xsl:text> </xsl:text>
<xsl:value-of select="name/last-name"/>
<xsl:text>
</xsl:text>
<xsl:value-of select="street"/>
<xsl:text>

</xsl:text>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Output:
Zip code 48392 (New York, WI):
Mr. Jack Smith
1234 Main Street
]]>