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Re: several messages about New Vocabularies in text/html

From: Ian Hickson <ian@hixie.ch>
Date: Wed, 2 Apr 2008 01:57:08 +0000 (UTC)
To: Sam Ruby <rubys@us.ibm.com>, Neil Soiffer <Neils@dessci.com>
Cc: public-html@w3.org, www-math@w3.org
Message-ID: <Pine.LNX.4.62.0804020116140.28180@hixie.dreamhostps.com>


On Tue, 1 Apr 2008, Sam Ruby wrote:
> >
> > I would expect that we would allow the xmlns="" attribute on <math> to 
> > have the MathML namespace, in the same way as we allow xmlns="" on 
> > <html> to contain the XHTML namespace. It wouldn't have any effect, 
> > though.
> 
> Such attributes will have an effect in IE8

Insofar as I can tell, they don't have an effect on IE8 Beta 1. At least, 
I have been unable to reproduce any behaviour that would cause us problems 
(there certainly is behaviour specific to xmlns="", but nothing that would 
be a blocker problem for this as far as I can tell).


> An alternative which would not constrain the evolution in such a matter 
> would be to enter yet another parsing mode when one encounters a given 
> bit of markup.

I have considered a number of such ideas, and all turned out to be fatally 
flawed in some way. I encourage you to contribute to the wiki:

   http://wiki.whatwg.org/wiki/Extensions
   http://wiki.whatwg.org/wiki/Diagrams_in_HTML

I have been unable to come up with a generic syntax for vocabulary 
extension that looks (even slightly) like XML and that would actually work 
in practice on the Web. Please, if you can come up with something that 
works, do. It would make my life much easier. :-)

(I haven't written up the ideas that I came up with that didn't work, 
because I mostly came up with them in the shower. Sorry.)


On Tue, 1 Apr 2008, Neil Soiffer wrote:
> 
> I meant that content MathML doesn't need to be directly supported.  
> However, it should be accepted as part of <annotation-xml>, where it is 
> easily ignored.

HTML5 today has about 110 elements. Presentational MathML has about 30. 
Content MathML has about 140.

_Doubling_ the number of elements allowed in text/html just so that all 
those elements can be ignored seems like a fundamentally bad idea. (It 
also more than doubles the number of elements that the parser has to know 
about.)

It should be pointed out that Content MathML really doesn't address any of 
the problems that I set out to solve for HTML5:

   http://wiki.whatwg.org/wiki/New_Vocabularies

...so it's a high cost for something that I'm not even trying to solve.

I understand that Content MathML theoretically is a good thing. I have 
nothing against it per se; indeed I would have much rather MathML only 
have Content MathML and not have Presenational MathML at all, though I 
understand the reasons for having both.

Consider. Users of MathML will likely be a minority (the <var> element is 
used on something like 0.03% of pages). Users of Content MathML are likely 
to be a minority even of those who consume MathML at all.

Should we really be dedicating _half of the language's vocabulary_ to such 
a small use case?


> However, I can do some searches, and they do show sematnics is widely used:
> 
> I did two searches:
> +mfrac +mi +mo +semantics
> +mfrac +mi +mo
> 
> The ratio of these numbers reveal the usage of <semantics>.  Unfortunately,
> search engines refuse to include <> in the search, so some pages that appear
> for "semantics" just have the word their, not the tag.  That doesn't seem to
> be too large a percentage though.
> 
> Because of well known issues with google and MathML, I did a search using
> three search engines:
> 
> google.com -- 75%
> +mfrac +mi +mo +semantics  71,500
> +mfrac +mi +mo 94,700

At least for Google, this search isn't giving you actual numbers about 
MathML usage, it's giving you numbers about pages that talk about MathML 
(which are generally much more likely to tell you how people _should_ do 
this, rather than how people _do_ do this.) I'll see if I can get any more 
reliable data.

If the data really does show that Content MathML is used a lot, then 
obviously it behooves us to find a solution that works for Content MathML 
in text/html as well. But if the data suggests that people simply don't 
use Content MathML in practice, then obviously this suggests that it's not 
worth the (not insignificant) effort to support it natively in text/html.

Especially given that we want browsers to do nothing with it.


On Tue, 1 Apr 2008, Neil Soiffer wrote:
> 
> Ian has already assured people that "classic MathML" will work in HTML5.  
> He said using a namespace prefix won't (Ian can you elaborate why you 
> just don't ignore the "xxx" <xxx:mi>?), but otherwise, the MathML spec, 
> user tutorials, and software can remain unchanged.

The main reason to avoid looking at prefixes, other than simple 
performance, is to avoid allowing people to do:

   <foo:math>
    <bar:mi> 1 </foo:mi>
    <baz:mo> !
   </math>

...or whatever even more crazy stuff they might come up with. The more we 
allow, the more people will get wrong.



I'll answer to all the e-mails in due course in more detail.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Wednesday, 2 April 2008 01:57:47 GMT

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