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Re: version 4.3.2

From: Masayasu Ishikawa <mimasa@w3.org>
Date: Tue, 10 Jul 2001 22:25:55 +0900
To: www-amaya@w3.org
Message-Id: <20010710222555V.mimasa@w3.mag.keio.ac.jp>
Vincent Quint <Vincent.Quint@inrialpes.fr> wrote:

> I guess you are referring to <!>
> This is not a comment. There is no reason for Amaya
> to recognize that character string as a comment.
> Refer to:
>    http://www.w3.org/TR/html401/intro/sgmltut.html#h-3.2.4
> or your favorite SGML documentation.

Well ... actually <!> is a valid (empty) comment declaration, at least
in an SGML sense.  HTML 4 spec is a bit unclear whether it allows empty
comment declaration, but HTML 2.0 (RFC 1866) allows empty comment
declaration and explicitly lists <!> as an example in "3.2.5. Comments" [1].

On the other hand, ISO/IEC 15445:2000 explicitly says "[t]here shall be
exactly one comment per comment declaration" in "12 Comments in HTML" [2],
so empty or multiple comments in a comment declaration is not allowed
in ISO/IEC 15445:2000, like XML.

Of course <!P> is an invalid declaration.

I would say, authors should avoid using empty comment declaration in
HTML, on the other hand, HTML user agents should tolerate it.

[1] http://www.w3.org/MarkUp/html-spec/html-spec_3.html#SEC3.2.5
[2] http://purl.org/NET/ISO+IEC.15445/15445.html#comment 

Masayasu Ishikawa / mimasa@w3.org
W3C - World Wide Web Consortium
Received on Tuesday, 10 July 2001 09:25:27 UTC

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