Definitions and Terminology in Section 9 - IdP

I have some comments and questions about terminology and naming in the Identity Provider APIs, Section 9.

I can�t figure out what is the different between an �identity assertion� (in the Section 9.2.3.1 definition of �assertion�) and a �payload of the identity assertion� (in the Section 9.2.3.3 definition of �contents�).  Are these the same thing?  I can�t seem to find a definition of either.

Section 5.7 of draft-ietf-rtcweb-security-arch-11 gives an example of �contents� as:

     "contents": "{\"fingerprint\":[ ... ]}"

which seems to imply that it is the fingerprint from the SDP.

Section 5.6.6 of the I-D also gives this example of �assertion�:

     "assertion": "{\"identity\":\"bob@example.org\",
                    \"contents\":\"abcdefghijklmnopqrstuvwyz\",
                    \"signature\":\"010203040506\"

which seems to imply that �contents� is a subset of �assertion�.  Is it required that the �contents� object in the �assertion� passed in validateAssertion be returned unchanged in the �contents� object of the promise?

Where is normative definition of the structure of the �identity assertion� and the �payload of the identity assertion� and the 'contents' and 'assertion' objects defined?

Also, in Section 9, �payload� means something very different from �payload� in the rest of the document, where is usually refers to an RTP payload.  Choosing a different word here might reduce confusion.

Examples 4 and 5 at the end of Section 9 aren�t very helpful, either.

Am I just not finding the relevant text?

Thanks,
Alan