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Re: application/mime and binary data

1997-07-29 16:05:02
Ned Freed wrote:

Adding a sentence to the spec is not sufficient--many existing
transports and such will happily transfer-encode subtypes of application
that they don't know anything about.

This case does not arise in practice since the contents of an
application/smime object are entirely 7bit. If there are lots of
out there that run around encoding purely 7bit data I certainly haven't
run into them.

Paul's proposal was that they have the same encoding restrictions as
multipart/* and message/*.  Such restrictions still permit the contents
to be 8bit or binary.

You seem to be proposing an additional restriction that the contents
conform to the restrictions of 7bit data.  That would then leave us with
a tunneling mechanism which is incapable of carrying a significant
portion of the MIME entities that are out there.

This was never the intent of the type. We get all the protection against
gratuitous change of encoding by restricting the encodings used inside of
multipart/signed to begin with.

A 7bit restriction on multipart/signed has about as much chance as being
followed as the 7bit restriction in SMTP.  It's real simple to
developers: follow this particular point of the specification and
overseas customers will drop your product like a hot potato.  The cost
of transfer-encoding everything is huge, and with the advent of such
things as UTF-8 it's going up.

Stuff encapsulated in this
type won't be readable by existing MIME implementations.

Depends on what you mean by "readable". It may not be processed as MIME,
but the text will be there as mostly-readable text.

If it's not processed as MIME, it's not readable.

If the contents are text, and the text is mostly restricted to US-ASCII,
and the user both has the presence of mind and goes through the trouble
of saving the thing to a file and bringing it up in a text viewer, then
the user can pick the text bits out of the surrounding cybercrud and
(probable) quoted-printable encoding.

Sending an application/mime to a public forum is going to be as much of
a disaster as sending a signedData.  In fact, I suspect it will be even
more of a disaster.  "It says this thing is a MIME, but I can't read it
with my MIME program.  That must mean MIME broken."