From the discussion so far I see the following issues that are as yet
unchanged in the spec and I believe need to be resolved:
1. The format should use multipart/related ordering and the MLE MUST
be the root part.
2. The MLE MUST be constructed with an atom:content/src="cid:..." and
that cid: URI MUST point to the included media.
2.1. A normative reference to cid: URI spec needs to be added.
3. Change multipart="yes" to be a non-boolean indicator, such
as post-options="multipart".
Presuming I haven't missed anything, I will come back
in a bit with camera ready copy proposals.
With respect to the issue of this specification 'using up' the multipart/related
media type, I believe that if later specifications come along that also
want to use multipart/related in a different manner then those follow-on
specifications can add a new parameter to the multipart/related media-type
to distinguish it from this specifications usage.