Before the detailed discussion on compression, or binary data in
general, I'd like to confirm that there is a consensus that CTE of
8bit or binary of MIME MUST be able to handle code points of non
graphic characters of ISO 2022 including NULL, a zero byte.
(why do I feel like we're about to get hit over the head with something?)
With the exception of a couple of warts in quoted-printable,
content-transfer-encodings don't care what kind of data is being encoded.
It can be audio or video or iso-2022 or unicode or whatever. Any kind of
data *can* be encoded with any c-t-e; the reason you pick one c-t-e over
another is to ensure robustness during transmission.
Specifically, either 8BIT or BINARY content-transfer-encoding can be used to
encode a 0x00. However, I doubt seriously that using the 8BIT label on a
body part that contains bare NULs is sufficient to protect the integrity of
that body part when handled by the various systems out there that recognize
the 8BIT content-transfer-encoding. BINARY labelling would be more
appropriate for body parts that contain 0x00 octets.
Anyway, I don't think you have the consensus you were looking for.
(But I'm sure you will push on anyway...)
Keith