我在我的XSLT中有以下代码块；

      <xsl:when test="StatusData/Status/Temperature > 27">
        <td bgcolor="#ffaaaa">              
          <xsl:value-of select="StatusData/Status/Temperature" />              
        </td>
      </xsl:when>

But as you might guess when the value is 34,5 instead of 34.5 it is recognised as a string which makes integer comparison not possible. I thought replacing , with . would be solution that needs a char replace. My question is how I can do this or It would be great to know more about string operations in XSLT...