- From: Philip Taylor <excors@gmail.com>
- Date: Thu, 03 May 2007 01:43:14 +0100
- To: public-html@w3.org
Patrick H. Lauke wrote: > I'm missing how subjecting B, I etc to the same processing rules and > definitions as any other unknown/removed/deprecated/obsoleted element > would break interoperability. At least for parsing, they need to be processed under different rules to unrecognised elements in order to be compatible with the existing HTML content. A document like: <!DOCTYPE HTML> <b> One <p> Two </b> Three is parsed to | <b> | " One " | <p> | <b> | " Two " | " Three " in FF3 and HTML5 (specifically html5lib), with the first two words being bold. It's parsed to a non-tree structure in IE6 but has the same rendering. Opera 9 parses it differently again, but does magic things outside the DOM to render it the same as everyone else. A document with unknown elements like: <!DOCTYPE HTML> <x> One <p> Two </x> Three is parsed to | <x> | " One " | <p> | " Two Three " in HTML5, identical to a <span>, and so a browser couldn't just parse it like that and then add "x { font-weight: bold }" to get the same effect as <b>. I'm not actually sure why HTML5 parses unknown elements and <span> in that way, since it doesn't match IE6, though I assume there's a reason somewhere... But in any case, other deprecated/removed elements like <xmp> do have to be explicitly specified with special parsing rules and not treated like unknown elements, otherwise some sites will be parsed very wrongly. So the specification has to 'support' all these elements in the sense of defining how they're processed by UAs (regardless of whether authors may or must not use them), rather than falling back on the behaviour for unrecognised elements, else it would be useless to anyone trying to parse the web (especially those who aren't already browser vendors with existing code that can handle these cases). (Whether <b>, <i> etc should be conforming for authors is a completely unrelated issue to whether the specification should tell UAs what processing rules to use for them, so it's best to avoid mixing those issues together - I'm only talking about the latter, since I believe that was your question in the quote.) -- Philip Taylor philip@zaynar.demon.co.uk
Received on Thursday, 3 May 2007 00:44:50 UTC