XSLT Reference

To produce output with two or more different cases, use the <xsl:choose> construct. It has one <xsl:when> element for each case, plus an optional <xsl:otherwise> element at the end for the “none of the above” case. Each <xsl:when> element has a test attribute whose value is an XPath expression; the first one that evaluates to a true value is processed.

Here's an example that outputs the content of the <turtle>children of the current node, and puts the first one in parentheses and the last one in square brackets.

    <xsl:for-each select="turtle">
      <xsl:choose>
        <xsl:when test="position() = 1">
          <xsl:text>(</xsl:text>
          <xsl:apply-templates select="."/>
          <xsl:text>)</xsl:text>
        </xsl:when>
        <xsl:when test="position() = count()">
          <xsl:text>[</xsl:text>
          <xsl:apply-templates select="."/>
          <xsl:text>]</xsl:text>
        </xsl:when>
        <xsl:otherwise>
          <xsl:apply-templates select="."/>
        </xsl:otherwise>
      </xsl:choose>      
    </xsl:for-each>