Let me carry Randall's and Stef's argument one step further.
"MAILASCII" really isn't ASCII, either. It is a carefully chosen
character collection, chosen for invariance across several character
sets. Its relationship with ASCII is that, for the characters it does
have, it uses the same codings as ASCII, but, by its nature, it also
uses the same codings as all of the ISO646 national variations and a few
other things.
So, if we need one of these things (I think we probably do, but I'd like
to keep the two discussions separate), let's choose a name that is
confusion-reducing, rather than confusion-creating. The following would
be plausible candidates:
MAILCII
INVARCII
Awful, aren't they? But no one is going to look at those and confuse
them with X3.4 ASCII (aka US-ASCII), or what has sometimes been called
ISCII (ISOSCII?), which are usually IS 8859 varients but somes basic
version ("invariant") ISO646.
Probably other, equally awful, names would do as well.
This might also help us remember that the normative 822 character set
is [US]ASCII, not MAILCII/INVARCII, or even, in the tradition of a side
discussion, Nathaniel-CII. :-)
--john