[RIF] section 6 - compatibility with RIF-BLD complete

All (and, in particular, Gary and Adrian),

I have completed the appendix about the compatibility between PRD and 
BLD [1] : I added a comparison table with all constructs in either PRD 
or BLD, with their PS and XML and a short section about the semantic 
compatibility, essentially saying that, when a doc is the same in PRd 
and BLD, then it means the same according to both dialects.

*Harold*, re garding the syntax, I did not add entries for 'Prefix' nor 
'Base' in the comparison table, because there is no such entries in the 
PS2XML translation table in BLD 4.3.2 (and I was too lazy to check in 
the XML schema)...

I will complete the comparison table as soons as the translation table 
is completed. Btw, maybe I should add an editor's note in the appendix, 
to warn, once again, that all this may change as PRD evolves?

Cheers,

Christian

[1] 
http://www.w3.org/2005/rules/wiki/PRD#Appendix:_Compatibility_with_RIF-BLD