Please help with Grouping & sorting ! ;-(

Hi,

I have some XML of the form

<catalogue>
        <item price="1" category="gold">this is a bracelet</item>
        <item price="5" category="Silver">this is a silver watch</item>
        <item price="1" category="gold">this is a ring</item>
        <item price="0" category="platinum">this is a platinum time
piece</item>
</catalogue>


What I want to do is make a webpage like :-

Platinum
        this is a platinum timepiece
Gold
        * this is a bracelet
        * this is a ring
Silver
        * this is a silver watch


I've managed to group & sort the data. My problem is detecting when a new
category appears and then spitting out the label as a Heading.

I have something like :-

  <xsl:variable name="previousCategory">XXX</xsl:variable>
  <xsl:for-each select="item">
        <xsl:sort select="@price" data-type="number" 
                  order="ascending"/>  
          <!-- If the category has changed then this is a new 
               "heading"
          -->
          <xsl:if test="@category[.!=$previousCategory]">
                <xsl:if test="@category[.!="XXX"]">
                        <!-- no more than a </UL> -->
                <xsl:call-template name="end_of_group"/>
            </xsl:if>
                <!-- new group = spit out new heading 
                        no more than a <UL> followed by the @category
                -->
            <xsl:call-template name="new_group"/>
          </xsl:if>
          <xsl:call-template name="item_element"/>
          <!-- Store this Category for the next iteration
                   so we know if we should display a new heading
             -->
          <xsl:variable name="previousCategory" select="@category"/>
    </xsl:for-each>

    <xsl:template name="item_element">
    <LI>
        <xsl:apply-templates/>
    </LI>
    </xsl:template>


What I actually see is :-

Platinum
        this is a platinum timepiece
Gold
        * this is a bracelet
Gold
        * this is a ring
Silver
        * this is a silver watch

Its ordered correctly BUT it does'nt realise that its already displayed a
heading (eg Gold) and its not supposed to show it again until it changes to
Silver. I think its because the variable previousCategory is write-once but
then how do I keep track of the previously displayed attribute "category" in
the previous sibling in the SORTED node set?

Help! ;-((

Amir

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