WS-Fragment: Another XPath subset

Looking at the upcoming WS-Fragment Working Draft, I see yet another  
XPath subset.
    http://www.w3.org/2002/ws/ra/snapshots/fpwd/frag/wsfrag.html#XPathL1

I wonder whether it's worthwhile to spend a little bit of time  
comparing motivations for their and our XPath subsets; we both seem to  
be solving for some notion of "constrained resources".

Regards,
--
Thomas Roessler, W3C  <tlr@w3.org>