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Re: [HTML5] 2.8 Character encodings

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Wed, 12 Aug 2009 14:15:37 +0200
To: public-html-comments@w3.org
Message-Id: <200908121415.37856.Dr.O.Hoffmann@gmx.de>
Julian Reschke:
> Ian Hickson wrote:
> > On Wed, 12 Aug 2009, Dr. Olaf Hoffmann wrote:
> >> Ian Hickson:
> >>> On Sat, 1 Aug 2009, Dr. Olaf Hoffmann wrote:
> >>>> There is no indication, that this might be 'HTML5'. Therefore no
> >>>> specific rule from the 'HTML5' draft needs to be applied.
> >>>
> >>> "text/html" is the indication that the HTML5 spec applies. (Or at
> >>> least, that will be the case once we update the text/html
> >>> registration.)
> >>
> >> This would be really a big backwards incompatibility, because
> >> it is not obvious, what to send for previous HTML versions.
> >
> > HTML5 describes how you handle documents intended for previous versions
> > as well, so that's not an issue.
>
> Well, except for the things it doesn't describe anymore.
>
> So I agree that the media type registration should remain in a
> stand-alone document, obsoleting RFC 2854, but keeping most the historic
> stuff in it.
>
> This may require an issue in the Issue tracker.
>
> BR, Julian

The meaning of some elements is different in 'HTML5'
as well or is defined in a more restrictive way, what excludes
some use cases possible in HTML4.
And has far as I have seen, those changes are not mentioned
in the current draft (as well as maybe some missing attributes).
If we take the sample of the version attribute itself, it does not 
define what it means, HTML4 for example does.
This simply shows, that the current 'HTML5' draft does not
indicate, how to interprete previous versions of HTML
documents in general, it indicates only, how to interprete 
'HTML5' documents and maybe how often used current 
browsers interprete current HTML documents 
(what can be wrong or incomplete).
A current draft cannot change the meaning of a previous
specification/recommendation and it does not change
the meaning of documents written in this previous language
version.


Because there are different versions for the same media type,
this mainly means, that one cannot derive such formal information
only from the media type. And it cannot be derived at all in some
cases, if no media type is available.

For XML formats with different versions there can be a similar
problem with the namespace. For example with XHTML+RDFa
there are some new attributes in the XHTML namespace, currently
not available in the 'HTML5' draft. Or this has and uses a 
version attribute, therefore surely there is a version indication
in the XHTML namespace, even if not defined by the current 
'HTML5' draft for the XML variant (it is defined as non conforming,
as far as I have seen).


Olaf
Received on Wednesday, 12 August 2009 12:25:08 GMT

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