2- Page 31
Mail gateways, relays, and other mail handling agents are
commonly known to alter the top-level header of an RFC 822
message. In particular, they frequently add, remove, or
reorder header fields. Such alterations are explicitly
forbidden for the encapsulated headers embedded in the bodies
of messages of type "message."
Since this seems to forbid any modification in the headers of an
encapsulated message, should not one add something like: 'On the
other hand, gateways may need to encode non-US-ASCII text in the
headers of an encapsulated message by using the mechanisms
described in RFC MIME-HEADERS.'
Headers are required to be US-ASCII. Any headers that do not consist
entirely of US-ASCII characters are not legal.
While gateways might do well to attempt to make them into legal
headers, this is outside the scope of the MIME specifications.
3- Page 32
No encoding other than "7bit", "8bit", or "binary" is
permitted for parts of type "message/rfc822". The message
+++++
Should be 'bodies' instead of 'parts' (a body of type 'message'
may happen in an message, not only in a body part).
Like it or not, the term 'body part' is now widely used for both
entire messages and components of a multipart (i.e. anything that can
have a content-type header). So messages are a subset of body parts.
Having separate names for body parts and messages doesn't help much,
because there aren't many traits that are unique to body parts that
aren't messages.
Either terminology can be used consistently within the MIME documents.
The way 'body part' is used in the current draft is more consistent
with normal usage.
Keith