W3C home > Mailing lists > Public > public-html@w3.org > March 2010

Re: Bug 7034

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Wed, 24 Mar 2010 07:33:02 +0100
To: Sam Ruby <rubys@intertwingly.net>
Cc: David Singer <singer@apple.com>, Henri Sivonen <hsivonen@iki.fi>, Maciej Stachowiak <mjs@apple.com>, Philip Taylor <pjt47@cam.ac.uk>, HTMLwg WG <public-html@w3.org>
Message-ID: <20100324073302365586.2311d623@xn--mlform-iua.no>
Sam Ruby, Tue, 23 Mar 2010 15:58:10 -0400:
> On 03/23/2010 03:41 PM, Leif Halvard Silli wrote:
>> Sam Ruby, Tue, 23 Mar 2010 10:24:15 -0400:
>>> On 03/23/2010 10:06 AM, David Singer wrote:
>>>> Thinking out loud here...

I'm commenting some old bits as well:
>>> There is a sincere desire by some people to require ampersands to be
>>> escaped, quote all attributes, close all open tags, get rid of tags
>>> such as acronym, and to rid the internet of the scourge that is
>>> presentational markup.

To opt-in to use XHTML syntax, can solve - and provide a rationale - 
for some syntactic issues. I agree. But when it comes to presentational 
markup, then that issue is not necessarily linked to a particular 
syntax. I suppose you have in mind  some kind of "strict" doctype. But 
in my book using <del> - instead of <strike> (which is only permitted 
in transitional mode) - to mark up text with line-through, can be 
compared to using <h1> to make text have a big font-size.

But in praxis, I guess I could live with saying that 
xmlns="http://www.w3.org/1999/xhtml" means that I have banned some 
elements. Give up some convenient features, for another, greater good, 
is OK. One has to draw a line somewhere. And what is considered 
semantic, is already pretty much settled - there is a definition of it, 
even if one disagree with it. Being able to use <strike> as long as I 
don't use xmlns, is already a bonus. For example: It is unfortunate 
that <strike> currently is linked to using a doctype which doesn't 
trigger 100% standards mode. There would be no such issue in HTML5 if 
"everything was permitted".

Also, as much as I gather, I would be able to embed <svg> in a document 
without the xmlns="http://www.w3.org/1999/xhtml" string - there is no 
limitation on that here. At least not for the "built-in" foreign 
namespaces that HTML5 supports out-of-the-box.

Are there any things that are possible to do when one uses the xmlns 
string, that shouldn't be allowed when one doesn't use it? 

<link /> should be permitted regardless.

If we say that extensions/foreign namespaces that are not part of the 
official HTML5 spec, has to happen in a document which uses the xmlns 
string, in order to be valid, would that be meaningful? I think it goes 
without saying that if one uses xmlns="http://www.w3.org/1999/xhtml", 
then also all foreign namespaces inside the document would also have to 
use xmlns, in order to be authoring requirements valid. And perhaps 
that is enough? Thus: that if you are able to extend the document 
without using xmlns="http://www.w3.org/1999/xhtml", then fine - go for 

One question is <p />: Currently <p /> is forbidden - validator.nu 
doesn't even permit it in polyglot mode, it seems. Yet, it has been 
permitted for 10 years. Or more: It is even permitted in HTML4 
documents. If it were to be permitted, then I guess it would have to 
have strict rules about when it would be permitted. But I don't know if 
it is worth fighting for that <p /> is permitted. (That said, the 
polyglot mode of validator.nu currently accepts a <p> without a closing 
</p> ...)

OTOH, should there be permission to write <video></video> and perhaps 
even <img></img> in the "xmlns authoring mode". Or in both authoring 

>> But if I want to specify a specific practise. The version attribute?
>> (e.g. version="XHTML+RDFa 1.0") And @profile? Additional namespace
>> declarations? A particular doctype? This is *pretty much* what we
>> have today. The xmlns in the<html>  start tag does represent a best
>> practise signal today. However, we could define what kind of best
>> practise it represents, better. Should any of the other practise
>> indicators (profile, version etc) depend on the presence of<html
>> xmlns="http://www.w3.org/1999/xhtml">? As an example: If I use<html
>> xmlns="http://www.w3.org/1999/xhtml">, then it could be expected that I
>> use XML compatible numeric character references. Whereas if I don't use
>> the xmlns attribute, then it would even be permitted with NCR without
>> the closing semicolon [bug 9300]. I could personally live with that.
> The latter part of this paragraph is what I was intending to explore. 
> The former part of this paragraph (specify a specific practice) is 
> something I would like to suggest:
> http://tinyurl.com/yagni

May be that is correct ... 

But what should be the relationship between xmlns and authoring 
requirements with regard to DOCTYPE be? Should the requirement to a 
_particular_ doctype be linked to the use of xmlns? Or should the only 
requirement be to not use a quirks mode triggering doctype? Is Almost 
Standards doctype OK?  Should I be able supply the 
xmlns="http://www.w3.org/1999/xhtml" to a standards mode triggering 
HTML4 doctype, and thereby be asked for this - yet to be defined - best 
practise? If yest, then it  would at least emphasize the principle.
>> And did you also mean that the presence of
>> xmlns="http://www.w3.org/1999/xhtml", does not per se change the
>> behavior of the user agent? But rather changes the behaviour of the
>> author, so to speak?
> Yes.

Are there any accessibility requirement issues that belongs to 
xmlns="http://www.w3.org/1999/xhtml"? Except that one would be using 
"safer code"?

>>> One downside of such an approach is that it would provide any means
>>> for people who author content intended to be served as
>>> application/xhtml+xml to opt out.
>> Or did you have in mind a text/html author who wants to break the best
>> practises that the xmlns implies, could simply opt out of the
>> requirements, by removing the xmlns = text/html best practise looses a
>> customer.
> No.  :-(
> Obviously, I wasn't clear.
> What I meant is that if I serve my content as application/xhtml+xml, 
> then the namespace is required.  If I then pass that content to a 
> validator, I need to buy into the ideology[1] that presentational 
> elements need to be avoided.
> I can live with that.

So I guess you mean that creating something that is serve-able as 
application/xhtml+xml doesn't mean that it has to fulfil the HTML5 
authoring best practises. So the downside is that the xmlns string will 
signify "best practise" inside a HTML5 document. But not inside a 
XHTML5 document? I have not checked Validator.nu with 
application/xhtml+xml too often, so don't know how much "ideology" it 
is in the XHTML5 mode ...

In application/xhtml+xml mode, then it is possible to drop some 
elements, as it is in text/html mode. But the effect is different. To 
ensure the same DOM tree, one must require all the elements that the 
DOM automatically creates in text/html mode, to be typed directly. 
Otherwise the XHTML document would create another tree than the 
text/html document would. I guess this could be part of the rationale?
leif halvard silli
Received on Wednesday, 24 March 2010 06:33:40 UTC

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