Suppose I have a XSL as follows:

    <xsl:stylesheet 
          xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
          version="1.0">
          <xsl:output method="html" encoding="utf-8" omit-xml-declaration="yes" indent="yes"/>
          <xsl:param name="sortKey" select="'firstname'"/>
       </xsl:stylesheet>

Then a XML as follows

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<?xml-stylesheet type="text/xsl" href="XYZ.xsl"?>
<ABC>
</ABC>

I want to pass a value to the XSL parameter firstname from XML. Can I do that? If yes, How? I'm not sure if I'm correct and this can be done.