-> Normally I use for-each and a test on the position:
->
->  <xsl:template match="/">
->    <xsl:for-each select="//heading[@class='2000'] |
->      //heading[@class='2003'] | //heading[@class='2008'] |
->      //heading[@class='2009']">
->      <xsl:apply-templates select="."/>
->      <xsl:if test="position() != last()">,</xsl:if>
->    <xsl:text>&#x0a;</xsl:text>
->    </xsl:for-each>
->  </xsl:template>
->
->  <xsl:template match="heading">
->    <xsl:value-of select="@class"/>
->  </xsl:template>