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RE: UTF-8 signature in web and email

From: Marco Cimarosti <marco.cimarosti@essetre.it>
Date: Wed, 16 May 2001 11:15:26 +0200
Message-ID: <27E7FB58F42CD5119C0D0002557C0CCA03F86D@XCHANGE>
To: 'Keld Jørn Simonsen' <keld@dkuug.dk>, duerst@w3.org
Cc: www-international@w3.org, Unicode List <unicode@unicode.org>
Keld Jørn Simonsen wrote:
> For UTF-8 there is no need to have a BOM, as there is only one
> way of serializing octets in UTF-8. There is no little-endian
> or big-endian. A BOM is superfluous and will be ignored.

Not so. In plain text, it is a useful signature to distinguish UTF-8 from
other things. See the 3rd question in
<http://www.unicode.org/unicode/faq/utf_bom.html>.

The three bytes EF BB BF is hardly confused with a meaningful sequence in
existing encodings. The only (unlikely) example I know is a couple of Hangul
syllables in UTF-16.

However, as we are talking about text whose encoding is already identified
(e-mail, web), it is in fact quite superfluous to have a signature at all.

But, then, this is superfluous also for other UTF's: what's the purpose of
using an endianness-ambiguous MIME specification (e.g. "UTF-16") and a BOM
to disambiguate it? Isn't it simpler to use an unambiguous specification in
the first place (e.g. "UTF-16BE" or "UTF-16LE")?

BTW, I understand that BOM is just a nickname now: the character has been
renamed as "ZERO WIDTH NO-BREAK SPACE".

_ Marco
Received on Wednesday, 16 May 2001 05:15:42 GMT

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