[Guidelines] Proposed update to section 4.5 (now 5.5), Designating Optional Behaviors

I took an editors action item to revise section 4.5 of the Guidelines  
(designating optional behaviors) to reflect the approach taken in the  
Web architecture document, to re-structure as problem statement, best  
practices and then example. [1]

This resulted in a fairly extensive edit so I am sharing the revision  
with the WG before completing the edits. I added some best practices  
based on the original text.

Attached are plain and red-lines, with revised section numbers due to  
a subsequent change to the documents to add summary section of best  
practices at the beginning of the document. (Will probably need to  
add informative reference to MTOM assertion)

regards, Frederick

Frederick Hirsch
Nokia

[1] <http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy- 
guidelines.html?rev=1.38&content-type=text/html;% 
20charset=iso-8859-1#optional-policy-assertion>