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Re: DTD/Schema level of validity

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Sat, 29 Mar 2003 09:14:56 +0100
To: Karl Dubost <karl@w3.org>
Cc: www-qa@w3.org
Message-ID: <3e975466.814840007@smtp.bjoern.hoehrmann.de>

* Karl Dubost wrote:
>Right now, we define the level of validity of a documents with 
>regards to its DTD. For example, the Markup validator validates 
>document against the DTD.
>With the coming of new technologies, often a schema AND a DTD are developed.
>The Schema being often more refined, more detailed than the DTD.
>For validity:
>	How do we define the validity of a document
>	when a schema and a DTD for the same technology
>	do not express the same constraints?

Validity is defined by the schema language and the schema document. When
a document instance meets the requirements of the associated schema
instance it's said to be valid. For example, XML 1.0 SE defines:

  An XML document is valid if it has an associated document type
  declaration and if the document complies with the constraints
  expressed in it.

When there are multiple assoicated schema instances for a given document
instance, you have multiple notions of Validity, if there is a DTD and a
W3C XML Schema and the document meets all their requirements, it's both,
XML-1.0-DTD-valid and W3C-XML-Schema-1.0-valid. I think it's not a good
idea to redefine document Validity, regardless of how many associated
schemas exist. For example, a XHTML 1.0 document with <img alt='text'
src='image' width='damn fat!' /> could be XML-1.0-DTD-valid but calling
it a Valid XHTML 1.0 document is at least misleading. XHTML 1.0 does not
(re-)define the term "valid" in it's context, defining validity should
be subject to schema languages only.
Received on Saturday, 29 March 2003 03:15:16 UTC

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