[xsl] Template for node-set parents

[Darren Oh <darren@xxxxxxx>]

I am trying to generate a stylesheet that copies an XML source document. The
only change should be that nodes selected by an XPath expression are sorted. I
want this to work for any XML source document. The only information available
to generate the stylesheet is the XPath expression and the sort criteria. I
think this requires creating a template for the parents of the nodes selected
by the XPath expression. How can I do this?