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Re: conformance constraints on producers that go beyond syntax

From: Jonathan Rees <jar@creativecommons.org>
Date: Mon, 21 Sep 2009 13:05:28 -0400
Message-ID: <760bcb2a0909211005u4d512d3kaff9ae34dd6ff7d2@mail.gmail.com>
To: "Henry S. Thompson" <ht@inf.ed.ac.uk>
Cc: www-tag@w3.org, Alan Ruttenberg <alanruttenberg@gmail.com>
Interesting. Out of curiosity I took a look at the specs (of course
I'd never think of doing this first : ). The HTML4 spec defines what
it means by conforming user agent and (implicitly) conforming
document, with a reference to SGML. It explicitly says that its advice
to authors is considered "good practice" and non-normative. There's
nothing suggesting that it inherits anything from SGML other than its
definition of conforming document. The HTML5 draft is careful to say
"This specification describes the conformance criteria for user agents
and documents" omitting any mention of authors. SGML has been
expunged. The bit about author good practice has been removed,
promoting the no-tag-abuse rule to normative status.

The words "authors must" occur several more times in the draft but in
each case (other than the one I quote) the constraint can be
operationalized as a constraint on documents, not on authors. (In
fact, since the constraint is only on authors, not documents, this
allows for the existence of conforming documents that cannot be
generated by any conforming author!) If I've identified all the author
conformance constraints, then we're left with no-tag-abuse as the sole
conformance constraint on authors (other than that they ought to
generate conforming documents).

Jonathan

On Mon, Sep 21, 2009 at 11:43 AM, Henry S. Thompson <ht@inf.ed.ac.uk> wrote:
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> Jonathan Rees writes:
>
>> (On an unrelated point - is the above requirement part of HTML4?
>
> Indirectly, at least, yes, insofar as HTML4 is an SGML application.
>
> The SGML spec. defines the 'document type definition' of an SGML
> application as specifying both the syntax _and_ semantics of the tags
> defined by that application, and documents are supposed to conform to
> document type definitions.  Violation of this is colloquially called
> 'tag abuse', i.e. using a tag for other than its documented purpose
> and is recognised in at least the old-school markup community (see
> e.g. [1]) as a Bad Thing.
>
> ht
>
> [1] http://www.xmlgrrl.com/publications/DSDTD/ch04.html#tag.abuse
> - --
>       Henry S. Thompson, School of Informatics, University of Edinburgh
>                         Half-time member of W3C Team
>      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
>                Fax: (44) 131 651-1426, e-mail: ht@inf.ed.ac.uk
>                       URL: http://www.ltg.ed.ac.uk/~ht/
> [mail really from me _always_ has this .sig -- mail without it is forged spam]
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Received on Monday, 21 September 2009 17:06:09 GMT

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