> I would like to support a new type of element, lets call it 
> <gl:numbered-item> which will have the item number instead of 
> a check box in front of it. So for each list with numbered 
> items in it, the XSL will need to calculate the position of 
> the sibling under the parent list. Can and should this be 
> done that way? 

Yes.

There are two ways of calculating the position: <xsl:number/> gives you the
number by counting siblings in the source tree, position() gets it by
counting nodes in the sequence selected by the calling xsl:apply-templates.
In your case, both give the same answer. The position() call is probably
more efficient, but it does create a hidden dependency between the two
template rules, which you may not like.

Regards,

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