Sorry, I think you got your documents mixed up. This sounds like the
licensing status of your software. MIME is as official a standard
as you can get on the Internet, and accordingly in the public domain.
It does contain some absolutes, for instance what you have to provide
as a minimum compliance. You MUST, for instance, support the
charset=USASCII and ISO-8859-x and NOTHING ELSE except with an X-
prefix for experimental use in private agreement between the parties.
You MUST support BOTH Quoted-Printable Content-Transfer-Encoding
and Base64 as well as 7-bit, 8-bit and binary. This latter provision
is because each encoding is optimal for a certain purpose, and it
would be detrimental to the net as a whole if an unsuitable encoding
is used due to an incomplete implementation. Further, it is possible
that the message arrives in another encoding than the one it was sent
in if some intermediate gateway recodes it to suit the receiving
part of the net. But apart from such mandatory items, the general
internet rule about partial implementations applies: Be generous
in what you receive and restrictive in what you send out.
Work is also nearing completion to make it official standard for news.
This will include such things as mandatory support of QP in header
lines, since most names outside the English-speaking world cannot
be written in USASCII.