W3C home > Mailing lists > Public > public-html@w3.org > October 2009

Re: ISSUE-41/ACTION-97 decentralized-extensibility

From: Philip Taylor <pjt47@cam.ac.uk>
Date: Thu, 01 Oct 2009 22:47:26 +0100
Message-ID: <4AC5236E.10502@cam.ac.uk>
To: Maciej Stachowiak <mjs@apple.com>
CC: Adrian Bateman <adrianba@microsoft.com>, HTML WG <public-html@w3.org>, Tony Ross <tross@microsoft.com>, Sam Ruby <rubys@intertwingly.net>
Maciej Stachowiak wrote:
> On Oct 1, 2009, at 1:22 PM, Adrian Bateman wrote:
>> The key differences:
>> * We don't support nested namespace declarations where one should 
>> override another
>> * We don't support the namespaces on attributes
>> * We only allow prefix declarations on the root element
> Here's a few more differences; I suspect more would be found with deeper 
> study:
> * In IE the localName, prefix and namespaceURI attributes whose values 
> are given by the proposal are entirely missing.
> * In IE, a tagUrn attribute that's not in the proposal is present, 
> holding the namespace URI.
> * in IE, the nodeName attribute value does not match what is proposed.
> * IE will not treat elements with localNames that match an existing HTML 
> element as the relevant HTML element, even if it has a namespace prefix 
> - the proposal does not include that behavior.

* IE has Element.scopeName
* IE has document.namespaces
* IE can bind prefixes with <xml:namespace prefix="v" /> and 
<?xml:namespace prefix="v" />
* document.write('<foo:bar>') will implicitly bind the foo prefix
* 'namespaced' elements with trailing slashes are parsed as empty elements.
* CSS selectors match on the full attribute name. (That means
     <html xmlns:foo>
     <style>foo\:bar { color: green }</style>
will match in all current browsers, but it would break under the 
proposal (unless CSS was changed).)

These issues have been discussed several times before, e.g. in 

There's some examples at 
http://philip.html5.org/demos/html/ie-xmlns/vml.html of IE's parsing and 

> Example: do we know how common it is for current text/html content to 
> have a namespace declaration somewhere other than the root element? All 
> such content would behave differently under the proposal than in IE, in 
> ways that may break intended behavior. Past studies (for example, 
> looking for copy-paste embedded SVG in text/html) imply this may be 
> fairly common.

http://philip.html5.org/data/xmlns-attributes.txt has some numbers for 
this kind of thing.

Philip Taylor
Received on Thursday, 1 October 2009 21:47:58 UTC

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