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The problems with namespaces in text/html (Was: MathML-in-HTML5)

From: Ian Hickson <ian@hixie.ch>
Date: Thu, 5 Oct 2006 19:40:45 +0000 (UTC)
To: juanrgonzaleza@canonicalscience.com
Cc: www-math@w3.org, dev-tech-mathml@lists.mozilla.org
Message-ID: <Pine.LNX.4.62.0610051928420.31492@dhalsim.dreamhost.com>

On Thu, 5 Oct 2006 juanrgonzaleza@canonicalscience.com wrote:
> Ian Hickson said:
> >
> > There are literally tens of millions of pages, for instance, that use 
> > the "xmlns" attribute on the <a> element,
> What is the problem with using the xmlns attribute on <a> or <html:a> 
> elements in a XML approach?

In browsers today, the following:

   <a href="test" xmlns=""> ... </a>

...is just a link. If we start supporting xmlns="" as it works in XML, but 
in HTML, then literally millions of pages are going to suddenly have their 
links stop working, because <a> in the "" namespace (as opposed to the 
XHTML namespace), is not an HTML <a>, and thus isn't a link.

I've seen hundreds of thousands of occurances of bogus meaningless things 
like this:

   <br xmlns="http://www.w3.org/TR/REC-html40">

...as well as many thousands of pages with xmlns="" values pointing to 
their own sites (as opposed to any sort of half-sensible namespace).

Some pages even have completely bogus namespaces on the root <html> 
element, which would make the entire page screw up. Even worse, Office 
HTML, of which there is a LOT on the Web, uses namespaces in a way to 
trigger IE to do one thing, but relies on the other browsers *not* 
handling the namespaces to make sure it all works everywhere. (Like I said 
earlier, I've worked with one browser vendor who tried implementing this 
namespace thing before, and had to back out because it broke real content 
in pretty fundamental ways.)

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Thursday, 5 October 2006 19:41:04 UTC

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