conditional XSL to XSL

Here is some minimal test input:
<?xml version="1.0" encoding="UTF-8"?>
<doc>
<el attr="x"/>
<el attr="y"/>
</doc>

Here is my stylesheet:
<x:stylesheet xmlns:x="http://www.w3.org/1999/XSL/Transform"
              xmlns:xsl="anything" version="1.0">
<x:output method="xml" indent="yes"/>
<x:namespace-alias stylesheet-prefix="xsl" result-prefix="x"/>
<x:template match="/">
  <xsl:stylesheet version="1.0">
    <x:apply-templates/>
   </xsl:stylesheet>
</x:template>
<x:template match="el">
  <x:if test="@attr = 'x'">
  <xsl:template match="tr[@class='title']">
    <xsl:value-of select="foo"/>
    <!--whole bunch of other complicated stuff-->
  </xsl:template>
  </x:if>
  <x:if test="not(@attr = 'x')">
  <xsl:template match="tr[@class='title' and position() &gt; 1]">
    <xsl:value-of select="foo"/>
    <!--whole bunch of other complicated stuff-->
  </xsl:template>
  </x:if>
</x:template>
</x:stylesheet>

Here is my problem (very real, even if the above seems contrived):
I would like to eliminate duplication in the above stylesheet by
conditionally
setting a variable, call it 'match-value',  and using it in the
"xsl:template" thingy,
which I think would work like this:
  <xsl:template match="{$match-value}">
    <xsl:value-of select="foo"/>
    <!--whole bunch of other complicated stuff-->
  </xsl:template>

So if that's right I would need to set the variable something like this:

<x:variable name="match-value">
  <x:if test="@attr = 'x'">
    <x:value-of select="'value1'"/>
  </x:if>
  <x:if test="not(@attr = 'x')">
    <x:value-of select="'value2'"/>
  </x:if>
</x:variable>

But I'm just not being able to get the right stuff into 'value1' (or
'value2');
I've tried things like:
        'tr[@class="title"]'
and
        'tr[@class=&#39;title&#39;]'
but I'm not getting any of saxon/xt/xalan to accept any thing like
these.

Jeff


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