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Re: "Pave The Cowpaths" Design Principle

From: Patrick H. Lauke <redux@splintered.co.uk>
Date: Sat, 12 May 2007 13:33:16 +0100
Message-ID: <4645B40C.3060900@splintered.co.uk>
To: www-html@w3.org

Henri Sivonen wrote:

> For example, it is more reasonable to require AT to walk the table model 
> up and to the left to find the header cell for a given data cell by 
> *default* than to expect authors to use id/headers in the simple cases. 

Yes, but the two aren't mutually exclusive: *if* there are no 
id/headers, or explicit scope attributes set to TH/TD, do the heuristics 
(as an error recovery or repair mechanism, if you will). However, if 
id/headers etc are detected, do NOT attempt to override them via 
heuristics, as this is what some AT currently does and it completely 
undermines any effort by conscientious authors. And worth noting that 
heuristics can only deal with simple tables...as soon as a table is 
complex, heuristics break. And there's often no easy way to tell simple 
from complex.

What if authors will produce complex tables without id/headers? 
Heuristics can have a stab at those, but don't expect the output to be 
dead on. And again, should they find the use of explicit markup like 
id/headers, they should use that instead. Certainly, this still leaves 
the scenario where misguided/sloppy authors/authoring tools put in the 
wrong id/headers, but I'd still say the AT should follow those (possibly 
offering a switch/function for users to say "override, and try to guess 
the meaning of this table").

Long story short: if the AT sees evidence of certain markup, it should 
go by that markup, not by heuristics, by default.

> There are few AT vendors and they have the capability to hire developers 
> who can write code that walks the table model instead of merely calling 
> getElementById(). OTOH, it is much harder to badger countless authors to 
> produce certain kind of attributes and do it correctly. Therefore, 
> making the simple cases Just Work with less author involvement is more 
> likely to lead to a net improvement of accessibility than insisting on 
> educating authors about more complex markup features.

And with the dual approach outlined above, everybody is happy. Full stop.

> P.S. Yeah, the above may require changes to AT, but I find it weird that 
> some accessibility advocates (perhaps not you) seem to have an implied 
> premise that AT cannot improve in response to HTML 5 but e.g. authoring 
> tools can.

Authoring tools are used by authors, so can prompt the actual author as 
their intent. AT sits at the far receiving end of the final output, and 
can't check back with the original author as to "what do you mean by this?"

P
-- 
Patrick H. Lauke
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Received on Saturday, 12 May 2007 12:33:21 GMT

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