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Re: xmlns in HTML5 (was: Telecon Agenda- Thursday 1500 UTC)

From: Steven Pemberton <Steven.Pemberton@cwi.nl>
Date: Thu, 16 Jul 2009 16:27:03 +0200
To: "Ian Hickson" <ian@hixie.ch>, "Manu Sporny" <msporny@digitalbazaar.com>
Cc: RDFa <public-rdf-in-xhtml-tf@w3.org>
Message-ID: <op.uw5zrdycsmjzpq@steven-750g>
On Thu, 16 Jul 2009 07:20:58 +0200, Ian Hickson <ian@hixie.ch> wrote:
> in the HTML5 spec, the only thing that
> decides whether a stream of bytes is "XHTML5" or "HTML5" is the MIME  
> type.
> There's no way to send XHTML5 as text/html, because if you send it as
> text/html, it is by definition HTML5. (This will probably be made more
> explicit once we update the relevant MIME type registrations.)

This is a POV error.

You may have seen the examples of programs that work both as Pascal and  
Fortran programs. It's a sort of sport. I have done similar things with C  
and sh, so that a file compiles itself; you feed it to sh, and the shell  
script part works out things about the C compiler and then feeds itself to  
the C compiler [1].

Now, is it a sh script? Yes. Is it a C program? Yes. It is both, and it  
only depends on what you feed it to how it gets processed.

We tried to allow the same sort of thing with XHTML 1, because we  
appreciated that it was going to be some time before browsers processed  
XML, but we knew that people with XML production pipelines were itching to  
get their XHTML documents out on to the web.

The much-maligned Appendic C guidelines of XHTML1 were only there to give  
some hints on how to do this.

So I can send XHTML5 as text/html if I want. It doesn't stop it being  
XHTML5, but it does change how it gets processed. Fine.

> The text that defines what ends up in the DOM is the parser:
>
>    http://www.whatwg.org/specs/web-apps/current-work/#parsing
>
> There are some complications around SVG and MathML (foreign content) in
> text/html, but ignoring those, "xmlns" attributes are handled the same as
> any unknown attributes in text/html.

I don't think anyone will contradict me if I say this chapter is, how  
shall I put it politely, "hard to read", but I have it on good authority  
that unknown attributes are left in the DOM. And they better be too,  
otherwise there's going to a lot of broken documents on the web soon, and  
future versions of HTML will break in HTML5 processors.

The upshot of this is that xmlns attributes will remain in the DOM. This  
is good. And it is all we need.

Steven

[1] http://www.cwi.nl/~steven/enquire.html
Received on Thursday, 16 July 2009 14:28:00 GMT

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