"MIME Content-types for SGML Documents" seems unclear

["Daniel W. Connolly" <connolly@xxxxxxx>]

My comments on this draft will come in two parts: in this message, I
comment on the clarity of the description of the mechanisms as
proposed. In another message, I'll criticize the mechanisms
themselves, and suggest a modification, using the SGML Open entity
catalog.

As an implementor of the receiving end of a MIME/SGML user agent, the
number one question I want answered from the spec is:

	From an application/sgml or multipart/sgml mime body part,
	how do I construct an SGML document entity for parsing?
	Then, how do I construct the other entities that comprise
	the document, and how are they identified?

Conversely, for the sending side, I need to know exactly this:

	Given an SGML document entity and the associcated collection
	of entities that comprise an SGML document, how do I
	construct a MIME body part for transmission?

In other words, how do I use MIME as an entity manager? I would very
much like to see the above two questions addressed explicitly in the
spec. They are answered in parts throughout the draft, but the result,
from my reading, is that they are answered incompletely.

The draft talks much about the logical structure of an SGML document:

	1.1 SGML
	...
	A complete SGML document consists of an SGML declaration, a
	prolog, and a document instance.

But I wish it gave more consideration to the _physical_ structure
of an SGML document, i.e. the entity structure of an SGML document,
which is all we need concern ourselves with for transmission.