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

Sun Oct 8 23:55:56 PDT 2006

Ian Hickson wrote:
> I'm not saying don't add MathML to HTML. I'm saying don't add namespace syntax to HTML. 

Is this feasible? As much as I'd like this for ease of use, at some point or 
other when enough things have been added to html, there will be conflicts. 
Namespaces seem like the only way to avoid those conflicts, and there needs to 
be some way of representing those namespaces.

Ian Hickson wrote:
> 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.)

OUCH.

Is the list of bogus namespaces relatively confined? Would it be technically 
feasible to enumerate the worst ones and say "ignore these"?

Are there any reasons besides ease of use and misuse in tag-soup content that 
XML's namespace syntax shouldn't be added to HTML?

-- 
dolphinling
<http://dolphinling.net/>