W3C home > Mailing lists > Public > www-international@w3.org > October to December 1996

Re: Accept-Charset support

From: Martin J. Duerst <mduerst@ifi.unizh.ch>
Date: Tue, 10 Dec 1996 16:36:10 +0100 (MET)
To: Klaus Weide <kweide@tezcat.com>
cc: Keld J|rn Simonsen <keld@dkuug.dk>, www-international@w3.org, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Message-ID: <Pine.SUN.3.95.961210163145.245I-100000@enoshima>
On Mon, 9 Dec 1996, Klaus Weide wrote:

> On Sun, 8 Dec 1996, Keld J&o/rn Simonsen wrote:
> > Koen Holtman writes:
> > 
> > > But skimming the UTF-8 specification, I gather that UTF-8 is an encoding
> > > mechanism, not a character set.
> > 
> > Well, no. UTF8 is an encoding of characters. It implies the character
>                                                ^^^^^^^^^^^^^^^^^^^^^^^^
> > repertoire of ISO 10646. So it is a charset in MIME sense, including
>   ^^^^^^^^^^^^^^^^^^^^^^^
> > the specific character definitions of 10646.
> 
> If that is taken seriously, then "Accept-Charset: utf-8" cannot be used
> to just send information about what character encoding a client can
> decode.  It implies that (at least when sent in the encoding of utf-8)
> all characters from the 10646 repertoire are acceptable.

Yes, all characters are acceptable up to the level of acceptability
that the HTML I18N spec requires. Which is not very much.


> It seems predictable that e.g. "Accept-Charset: koi8-r,iso-8859-1,utf-8"
> will be used to indicate "documents containing characters which are 
> also in koi8-r and latin-1 characters are acceptable in utf-8 encoding", 
> because there is currently no better way to express that (other than
> maybe with language tags, which has other problems already mentioned:
> e.g. transliteration/transcription, languages that do not imply exactly
> one character repertoire).

There is no real need to express subrepertoiries.


> This is of course not specific to HTTP or the Web, protocols without
> negotiation like mail need charset labelling.  A simple MIME compliant
> MUA should have sufficient information from message headers to dispatch 
> to the appropriate viewer.  In the pre-UTF era this was reliably possible 
> e.g. with metamail (given the correct charset parameter and availability of
> appropriate codepage).  With messages labelled "utf-8", heuristics have to 
> be involved.

The concept of having a different viewer for every "charset" is still
widespread, but rather outdated and doomed. For a network computer
running Java, being able to display all of Unicode/ISO 10646 is
just a must. It might be a pain for older and more expensive
technology to follow, but that's their problem, not ours.

Regards,	Martin.
Received on Tuesday, 10 December 1996 10:36:38 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 2 June 2009 19:16:46 GMT