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Re: XHTML 2.0 - 3.2 Conformance Requirements (PR#7651)

From: Justin Wood (Callek) <116057@bacon.qcc.mass.edu>
Date: Fri, 27 May 2005 15:59:10 -0400
Message-ID: <42977C0E.5010806@bacon.qcc.mass.edu>
To: Shane McCarron <shane@aptest.com>
CC: w3c-html-wg@w3.org, www-html-editor@w3.org, Jim Ley <jim.ley@gmail.com>

Shane McCarron wrote:

...[cut much of message]...

>>
>> The point being that there are XHTML 2.0 elements within elements of a
>> namespace that are not understood, my concern in the issue is that by
>> rendering the XHTML 2.0 elements inside the SVG fragment the meaning
>> of the document will change, and that in such a case we do not have
>> acceptable compatibility with XHTML 2.0 only user agents.   I
>> therefore reject the response to the issue, perhaps that was because
>> it wasn't clear, in which case please raise another issue.
>>  
>>
> I think your issue was clear to everyone who discussed it.  In XHTML 
> 2, if your concern is that the meaning of a document might change if a 
> certain facility is not available, you can use the fallback mechanisms 
> associated with the src attribute... for example:

...

> Note, however, that in a hybrid document type that merged SVG with 
> XHTML, this would be a little counter-intuitive for content 
> developers.  I appreciate that you have identified a situation where 
> you would not want the content to be rendered.  I could show many many 
> examples where I would want it to be rendered.  The book is not closed 
> on this issue, but at this time the Working Group has no ready 
> solution that will satisfy both camps.  We would certainly welcome a 
> proposal to that end, if you have one.
>
In my opinion using src="" is _not_ the solution for a mixed namespace 
document and fallback mechanics.

That said, may I ask what the harm would be in, for example, an 
attribute in the xhtml namespace, |fallback="no"| which specifies 
whether fallback content should be used or not, and given that at least 
both me and you can agree that the most frequent use would dictate that 
fallback="yes" leave that the default.

This will not specify if content should be rendered (display can likely 
handle that in some way), but if the "use" of a tag be unknown to a UA, 
should the UA then try and utilize underlying content, such as that svg 
example.

In my opinion, a real-world-example of why fallback content is bad, is 
enough to warrant at the least a toggle.

You are free to present this as a formal issue, or simply converse with 
me (on the [public] list) regarding it prior to raising the issue.

~Justin Wood (Callek)
[Let me note here, incase this is raised as a formal issue; should this 
e-mail address fail to work, Callek@gmail.com will continue (I have yet 
to migrate these lists over to that)]
Received on Friday, 27 May 2005 19:59:34 GMT

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