W3C home > Mailing lists > Public > www-html@w3.org > January 2009

Re: HTML 5 and XHTML 2 combined

From: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>
Date: Fri, 09 Jan 2009 00:23:43 +0000
Message-ID: <4966990F.1070606@googlemail.com>
To: Dustin Boyd <rpgfan3233@gmail.com>
CC: www-html@w3.org, Mark Birbeck <mark.birbeck@webbackplane.com>, Brett Patterson <inspiron.pattersonb@gmail.com>, David Woolley <forums@david-woolley.me.uk>, Molte <molte93@gmail.com>, Shavkat Karimov <shavkat@seomanager.com>

On 8/1/09 22:47, Dustin Boyd wrote:
> - Different multimedia formats, different programming languages and
> even different ways to deliver a package were all designed with
> different goals in mind, so why is it that HTML 5 and XHTML 2.0 are
> unable to coexist?

I don't see any reason why they can't coexist so long as processing
requirements for HTML5 do not conflict with processing requirements for
XHTML 2. As far as I know, they haven't since XHTML 2 moved out of the
XHTML1 namespace.

> What might prevent HTML 5 and XHTML 2.0 from serving the same content
> with different markup, if anything?

That may depend what "HTML 5" and "XHTML 2.0" mean here.

"A strictly conforming XHTML 2.0 document" uses _only_ features defined
in the XHTML 2.0 Specification; for example it would exclude SVG and MathML:

http://www.w3.org/TR/xhtml2/conformance.html#strict

But there's no equivalent concept in the HTML5 draft, where an XHTML
document is just a document using features from HTML5:

http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#conformance-requirements

And the text/html serialization of HTML5 includes SVG and MathML.

> It is my opinion that they should be able to coexist peacefully.
> Who said browser vendors COULDN'T or WOULDN'T support both?

Now that XHTML2 has stopped using the same namespace as XHTML1, it seems
that browser vendors could indeed support both the XML serialization of
HTML5 and the XML serialization of XHTML 2, assuming either
specification is implementable on its own.

> The only disadvantage that XHTML 2.0 has is that it relies upon
> other specifications like Ruby, XForms, XML Events, etc.

This reliance is actually a design goal of XHTML 2.0: "As generic XML as
possible: if a facility exists in XML, try to use that rather than
duplicating it."

http://www.w3.org/TR/xhtml2/introduction.html#aims

> However, it isn't as if every browser MUST implement all of XHTML
> 2.0. After all, text browsers like Lynx wouldn't necessarily need to
> implement XML Events when implementing XHTML 2.0, right?

If a browser implements only a selection of XHTML 2.0 modules, they have
not implemented XHTML 2.0:

http://www.w3.org/TR/xhtml2/conformance.html#s_conform_user_agent

I don't think the output media of a browser has any special relevance to
whether it should implement XML Events or not.

> The same can be said of AUDIO, VIDEO, OBJECT and CANVAS elements for
> a likewise implementation of HTML 5.

No, all user agents are required to implement those elements in HTML5.
See the spec if you have questions about _how_ to implement them, and if
it's still not clear, let the HTML WG or WHATWG know.

For the "video" element, the draft says:

"User agents that cannot render the video may instead make the element
represent a link to an external video playback utility or to the video
data itself."

http://www.whatwg.org/specs/web-apps/current-work/#video

For the "canvas" element, the draft says:

"In non-visual media, and in visual media if scripting is disabled for
the canvas element, the canvas element represents its fallback content
instead."

http://www.whatwg.org/specs/web-apps/current-work/#the-canvas-element

For the "audio" element, the draft says:

"User agents must support the WAVE container format with audio encoded
using the PCM format."

http://www.whatwg.org/specs/web-apps/current-work/#audio

--
Benjamin Hawkes-Lewis
Received on Friday, 9 January 2009 00:24:26 GMT

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