This is a new area for me. Need to eliminate duplicates that occur
within sub-groups.

XML Input example:
<?xml version="1.0"?>
<root>
	<boxes>
		<box_sizes>
			<value>square</value>
		</box_sizes>
		<box_sizes>
			<value>square</value>
		</box_sizes>
	</boxes>
	<boxes>
		<box_sizes>
			<value>round</value>
		</box_sizes>
		<box_sizes>
			<value>square</value>
		</box_sizes>
	</boxes>
	<color1>red</color1>
	<color2>blue</color2>
</root>

Desired output:
<?xml version="1.0" encoding="utf-8"?>
<root>
	<color1>red</color1>
	<boxes>
		<box_sizes>
			<value>square</value>
		</box_sizes>
	</boxes>
	<boxes>
		<box_sizes>
			<value>round</value>
			<value>square</value>
		</box_sizes>
	</boxes>
</root>

As you can see, I want to eliminate duplicate occurances of
<box_sizes/value> within the <boxes> group.

<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="1.0">

  <xsl:key name="by-value"
           match="box_sizes"
           use="concat(generate-id(parent::boxes), '_', value)"/>

  <xsl:template match="root">
    <xsl:copy>
      <xsl:apply-templates select="color1"/>
      <xsl:apply-templates select="boxes"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="*">
    <xsl:copy>
      <xsl:apply-templates/>
    </xsl:copy>
  </xsl:template>

	Martin Honnen
	http://JavaScript.FAQTs.com/