Excerpts from ext.ietf-822: 10-Mar-98 Re: overdefining text/plain? Chris
Newman(_at_)innosoft(_dot_)co (848*)
The rule which
requires MIME MUAs to treat unrecognized subtypes of text as "text/plain"
is documented in both RFC 2046 and RFC 2049. The fact that three MIME
MUAs failed one of the most basic MIME requirements is unacceptable.
Isn't the problem here really that (1) customer demand trumps standards,
and (2) as Laurence pointed out, some folks are registering (and using!)
invalid subtypes of "text", like "text/html", "text/sgml", and
"text/rtf"? MUA vendors don't want to put gibberish up on their
customer's screens, and there are registered subtypes of "text" which
look like gibberish to normal users when presented directly, so the only
sensible MUA rule for commercial vendors is to censor anything they
don't know to be correctly presentable.
I remember raising this point during the original MIME discussions (when
some folks were proposing text/postscript :-). The fact is, by allowing
arbitrary registration, we remove the ability to say anything in general
about the so-called top-level media types, because people are always
going to misuse them. I'd suggest just facing that fact, and removing
any RFC requirements that are supposed to apply to all instances of any
top-level type.
Bill