xsl:sort/@case-order feature missed

Hi,

we are missing a neutral value for the
xsl:sort/@case-order. We are using a 

	<xsl:sort ... case-order='{$which-order}'>

within a parametrized template and would like
to have all three cases for which-order:

	1. lower-first
	2. upper-first
	3. no-particular-ordering-on-upper-and-lower

Since we are using xsl:variables we cannot simply
leave the case-order attribute away.

Either this seems to be missing from the XSLT 
standards, even XSLT 2, or I'm missing the point,
e.g. an empty case-order would have the effect of
the third line. And if I'm not missing the point,
wouldn't this be useful within XSLT 2.0?!

--
Frank Nestel

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list