exclude-result-prefixes

In the following stylesheet I use the document function to access the
current stylesheet in order copy the contents of a variable. The reason
I do this is because the stylesheet is built dynamically and the
variable may not exist. 

The problem is the xsl namespace attached to the <tr> element in the
output. How do I exclude that?

I tried adding exclude-result-prefixes="xsl" to the <tr> element inside
the variable but it didn't work. 

Thanks,
Kevin Collins


XSL:
<xsl:stylesheet 
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; 
   version="1.0">
   <xsl:output method="xml" indent="yes" />
        
   <xsl:template match="/">
      <table>
         <xsl:copy-of 
 
select="document('')/*/xsl:variable[(_at_)name='optionalstuff']/*" />
         <tr>
            <td>Common stuff here.</td>
         </tr>
      </table>
   </xsl:template>

   <xsl:variable name="optionalstuff">
      <tr>
         <td>Optional stuff here.</td>
      </tr>
   </xsl:variable>

</xsl:stylesheet>

Output:
<table>
   <tr xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
      <td>Optional stuff here.</td> 
   </tr>
   <tr>
      <td>Common stuff here.</td> 
   </tr>
</table>