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Re: My page doesn't validate

From: Masayasu Ishikawa <mimasa@w3.org>
Date: Wed, 26 Jun 2002 16:18:51 +0900 (JST)
Message-Id: <20020626.161851.104036493.mimasa@w3.org>
To: hallem@rpi.edu
Cc: www-validator@w3.org

"Michael Hallett" <hallem@rpi.edu> wrote:

> I poked around the implementation DTD's for XHTML 1.1 and the Frames
> Module and came to the conclusion that the redefinition of html.content
> in the Frames Module wasn't being processed.

Because according to "4.2 Entity Declarations" of XML 1.0, "[i]f
the same entity is declared more than once, the first declaration
encountered is binding", so in your DTD, the declaration of
%html.content; in the Structure Module referenced from the XHTML 1.1
DTD is binding.

On the other hand if you bring in the Frames Module before the XHTML
1.1 DTD, you'll get another parameter entity problems.  This is
well-known nasty chicken-and-egg problem of DTD, and you'll have to 
include a redundant declaration of %html.content; before you bring in
the XHTML 1.1 DTD in addition to the Frames Module which should be
brought in after the XHTML 1.1 DTD.

I know it's ugly, but that's how DTD works.  It would be easier to
write your DTD by modifying the XHTML 1.1 DTD driver rather than
referencing it and cope with chicken-and-egg problems.

And this is not really a validator's issue, please move to
the www-html@w3.org list if you want to continue the discussion
about XHTML DTD implementation.

Masayasu Ishikawa / mimasa@w3.org
W3C - World Wide Web Consortium
Received on Wednesday, 26 June 2002 03:18:53 UTC

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