Re: UTF-7 is dead

From: Joerg Knappen (KNAPPEN@alpha.ntp.springer.de)
Date: Wed May 26 1999 - 07:00:41 EDT


Pete Resnick schrieb:

> a) Most environments are now 8-bit safe, and more are moving that way
> all of the time.

It is less than clear, what the term "8-bit-safe" means. In practice it
often means: 8-bit-safe except C0 controls AND C1 controls. Fully 8-bit-safe
text transports are still rare (and will remain so, I'm afraid).

> b) In those cases where only 7-bit is available, UTF-8 (which is a
> charset, not an encoding) can itself be encoded as quoted-printable
> or base64.

Not a real solution -- in this case one can as well encode UCS-2 as base64.

There are some proposals, however:

Unicode technical report No. 16 (http://www.unicode.org/unicode/reports/tr16/)
contains a proposal backed by IBM for uft-8m without C1 controls and
utf-8-ebcdic for passing utf-8m octetts thru EBCDIC hosts.

There is also utf-7d5 (see: http://vzdmzi.zdv.uni-mainz.de/~knappen/jk009.html
and http://vzdmzj.zdv.uni-mainz.de/~knappen/jk010.html). The main difference
is, that utf-7d5 only aims at ucs-2, while utf-8m covers full ucs-4 (31bit).

--J"org Knappen



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