Conformance model of RDF specs?

Hi,

I understand it is too late for making Last Call comments, so I'm
sending these remarks just as generic feedback to the WG; feel free to
do whatever you want with them process-wise, but I would be very
interested in getting answers to my questions.

Basically, I started to work a smallish specification built upon RDF,
and I'm not finding the following information that I would think are
indispensable for anybody wanting to build something on top of RDF:
- is there a list of what SpecGL [1] calls "classes of products" for the
various RDF specs? e.g., is the notion of RDF parser defined somewhere?
RDF document? 
- is there a list of requirements bound to these classes of products?
e.g., is a RDF/XML parser required to be a validating XML parser? Is
there a minimal list of encodings that an RDF/XML parser should support?
- How the requirements between semantics/model & syntax/vocabulary play
together?

Sorry for the late comments, and thanks for any feedback.

Dom

1.
http://www.w3.org/TR/2003/CR-qaframe-spec-20031110/definitions#def-cop
-- 
Dominique Hazaël-Massieux - http://www.w3.org/People/Dom/
W3C/ERCIM
mailto:dom@w3.org