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The failure of Appendix C as a transition technique (was: Re: Draft Minutes of 2013-02-14 TAG telcon)

From: Henri Sivonen <hsivonen@iki.fi>
Date: Tue, 19 Feb 2013 14:34:35 +0200
Message-ID: <CAJQvAue++2gTMBCL1iZeOCDwaa8tKBjT21HxS6TPUokaERB0JQ@mail.gmail.com>
To: "www-tag@w3.org List" <www-tag@w3.org>
On Thu, Feb 14, 2013 at 10:20 PM, Jeni Tennison <jeni@jenitennison.com> wrote:
> Masinter: thinking about polyglot as a general technique not
>    just for languages, but for APIs and network protocols, as a
>    transition technique from one version to another or one
>    language to another, or one extension to another
>    ... if you need to make changes, "polyglot" is a transition
>    technique
>    ... Appendix C in XHTML was a transition technique from HTML to
>    XHTML

It's worth noting that Appendix C failed as a transition technique.
This isn't something caused by IE later on. Appendix C had failed by
the fall of 2000.

In December of 2000, before the release of Netscape 6, Gecko had an
HTML parser mode called the Strict DTD. The "DTD" wasn't an SGML DTD.
Instead, it was a C++ class that implemented the containment rules
declared in the SGML DTD. Strict DTD threw away a markup that violated
the HTML 4 Strict containment rules but didn't stop parsing up our

By August, testing was indicating that the "Strict DTD" parser feature
was not Web-compatible. But that's another story. The relevant part
here is that the Strict DTD was being used for XHTML 1.0 Transitional
served as text/html and was seen as a problem in that context. David
Baron argued that this was a forward-compatibility problem with future
XHTML DTDs/schemas.

(The entire thread is an interesting read with the benefit of
hindsight. You can see I was still an XHTML believer at that time.)

The thread resulted in a telecon, where, among other things, it was decided:
"- Parse XHTML delivered as text/html using the XML content sink with
an HTML document. (Instead of using the Strict DTD, which we do

That decision lasted for less than a month. IIRC, it was already too
late to parse even the front page of O'Reilly's xml.com as XML. Hixie
and dbaron asked the HTML WG what to do:
(Note: Member-confidential message, but the existence of the message
is disclosed by the next link in this message. )

The HTML WG responded (in public) that text/html should be treated as
HTML: http://lists.w3.org/Archives/Public/www-html/2000Sep/0024.html

And so it has been ever since. Appendix C content wasn't transitioning anywhere.

Henri Sivonen
Received on Tuesday, 19 February 2013 12:35:04 UTC

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