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HTML5 defines error handling (Was: MathML-in-HTML5)

On Thu, 5 Oct 2006, White Lynx wrote:
> > 
> > In the context of HTML5 the term "tag soup" is meaningless, since 
> > there is no UA-defined handling anymore
> 
> Error handling comes naturally and developers are not supposed to put 
> all resources into area that provides no real functionality. It is UA 
> defined and I don't know how HTML5 is suupposed to change it if the UA 
> that defines error handling today does not participate in the process 
> and due to its share faces no error handling problems in the way others 
> face them.

In the case of HTML5 (like in CSS, for that matter), error handling is 
*not* UA-defined -- it is strictly defined by the specification and user 
agents must follow the rules in the specification for handling errors.

   http://whatwg.org/specs/web-apps/current-work/#parsing

In fact, no distinction is made between error conditions and normal 
conditions, there is just one set of rules that works for all content, 
whether valid or not (although error conditions are called in the 
appropriate places).


> If all do their own thing today then how HTML5 parsing rules could could 
> be compatible with the way how browsers handle incorrect ("tag soup") 
> documents today.

I did a lot of extensive research before documenting the HTML5 parsing 
rules, to ensure that the common aspects, which documents depend on, were 
carried forward, while the more unique aspects, which documents did not 
depend on, were simplified and unified.


> And once again let me note that MathML community does not have tagsoup
> parsing problems today

If we go with the HTML5 route, it will continue not having such problems, 
since HTML5 strictly defines how all content is parsed.


> ...at the moment I see only one UA that wants to go in this way, I don't 
> think that others will follow it, in case of MathML tag soup at least. 
> HTML tag soup as such may be different issue as here browsers have 
> motivation coming from the large amount of legacy content so if HTML5 
> will reverse engineer MSIE error handling and document it others may 
> find it useful, but once gain this is not an issue for MathML 
> implementations where we lack implementations in browsers (so even 
> absolutely valid markup is not treated properly) and are talking about 
> specifying comprehensive error handling that people are supposed to 
> devote time and resources to.

The parsing (and error handling) rules for the proposed math-in-HTML5 is a 
_subset_ of the general HTML5 parsing (and error handling) rules, such 
that any browser that implements HTML5 parsing automatically is compatible 
with HTML5+Math parsing. (The only requirement then is that the UA also 
implement MathML itself, so that the resulting DOM is handled per MathML 
rules.)

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

Received on Thursday, 5 October 2006 19:59:02 UTC