W3C home > Mailing lists > Public > public-html@w3.org > May 2007

Re: Support Existing Content

From: Julian Reschke <julian.reschke@gmx.de>
Date: Fri, 04 May 2007 13:48:13 +0200
Message-ID: <463B1D7D.4050502@gmx.de>
To: Anne van Kesteren <annevk@opera.com>
CC: HTML WG <public-html@w3.org>

Anne van Kesteren wrote:
> 
> On Fri, 04 May 2007 13:09:30 +0200, Julian Reschke 
> <julian.reschke@gmx.de> wrote:
>> But what's the point in defining an additional conformance class, if 
>> it doesn't make any difference in practice? (Methinks this is exactly 
>> what you said yourself just a few messages ago).
> 
> To allow for extensbility of the language in the future. By discouraging 
> people from using non-conformant constructs we can in the future 
> introduce some additional parsing rules for new elements, for instance.

I think if we really want to discourage people, we need to do more than 
flag that in conformance checkers. Remember: most people don't use them.

> This is comparable with how 'color:foobar' works in CSS. foobar is 
> currently not a conforming value for the 'color' property. This 
> discourages people from relying on 'color:foobar'. In the future the 
> 'color' property could get a value 'foobar' that does something new in a 
> compatible way as older user agents will simply ignore it.

I don't get that example: "color:foobar" (as far as I understand) just 
has no effect, so if people *meant* to set a color, they will fix their 
CSS.

Contrary to that, there doesn't seem to be a reason for authors to 
produce conforming HTML5, if conforming processors are required to 
accept tag soup anyway. If the tag soup does what the author intended, 
why would she/he change it (unless she/he belongs to the small group of 
authors who already believe in producing conforming documents?).

> The other advantage of keeping the conformant class smaller in this 
> particular case is to encourage authors to write documents that are 
> backwards compatible with older user agents. Because relying on some of 
> the specific quirks in the HTML5 parser algorithm might not guarentee 
> that. The error handling has evolved over the years and some browsers 
> may not recover in the same way as others currently.

Playing the devil's advocate: in which case the best enocuragement for 
authors to produce conforming documents would be if UAs did *not* use 
the HTML5 parser, making it essential for authors to produce conforming 
docs in the first place.

Best regards, Julian
Received on Friday, 4 May 2007 11:48:44 UTC

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