> > 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.

I think it's only a number as long as it doesn't get overridden - as
soon as you pass in the value a parameter it becomes a string.  For
example this XML:

<group>
	<menu>1</menu>
	<menu>2</menu>
	<menu>3</menu>
	<menu>4</menu>
	<menu>5</menu>
	<menu>6</menu>
</group>

And this stylesheet:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:param name="pos" select="5"/>

<xsl:template match="/">
  <xsl:apply-templates select="(//menu)[$pos]"/>
</xsl:template>

</xsl:stylesheet>

Transformed without specifying a parameter produces the result:

5

Pass in the parameter 'pos' a value of '5' and the result is:

123456

This is consistent across processors.

In XSLT 1.0 the number() function ensures $pos is treated as a number,
2.0 the 'as' attribute on the param does the job.

cheers
andrew