> The $pos is defined like 
> 
> 	<xsl:param name="pos" select="0"/>

That's certainly a number, and since positions start at 1, xyz[$pos] should
always be an empty sequence (node-set). If, as you say, one processor is
behaving differently from all the others, then that's prima facie evidence
of a bug.

Michael Kay
http://www.saxonica.com/