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Re: versioning, robustness principle, doctypes etc

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Fri, 04 Sep 2009 15:40:17 +0100
To: Henri Sivonen <hsivonen@iki.fi>
Cc: Bjoern Hoehrmann <derhoermi@gmx.net>, www-tag@w3.org
Message-ID: <f5b8wgupycu.fsf@hildegard.inf.ed.ac.uk>
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Henri Sivonen writes:

>> * Henri Sivonen wrote:
>>> Having an in-band version indicator for conformance checking makes
>>> the
>>> following unwritten assumptions:
>>>
>>> * It's appropriate for a person opting to target an older "version"
>>> not to see more up-to-date advice. (Surely newer advice should be
>>> assumed to be better informed and, thus, better advice.)
. . .
>
> I'm assuming that if language level n+1 makes something non-conforming
> that was conforming in language level n, the newer spec does so for a
> good reason. If people have language level n version identifiers in
> their documents, they miss out on this important advice.
>
> Basically if current wisdom is that <font> is evil, <font> doesn't
> become less evil if you add an HTML 4.01 Transitional doctype.

_This_ assumes that the semantics of version identifiers is "All
consumers of this document should behave as if they were operating
with respect to the named version."  The semantics that I would like
to see, and which I believe is what others arguing for the utility of
an optional version identifier would agree with, is "This document was
authored with the named version in mind -- consumers take note."  The
latter interpretation is entirely consistent with a conformance
checker saying

 "1) Conformant to V[specified];
  2) Features xxx and yyy of V[specified] are now deprecated -- see
     [appropriate migration information]"

ht
- -- 
       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 Friday, 4 September 2009 14:40:56 GMT

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