- From: Henri Sivonen <hsivonen@iki.fi>
- Date: Mon, 14 Apr 2008 16:08:40 +0300
- To: Al Gilman <Alfred.S.Gilman@IEEE.org>
- Cc: HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>, public html for all <list@html4all.org>
On Apr 14, 2008, at 15:07, Al Gilman wrote: > By the continuity (minimize change) values of the HTML WG, it is the > change that must demonstrate necessity. I don't think the HTML WG has a 'minimize change' value in the conformance department. > So far nobody has demonstrated the necessity of making @alt optional. Saying 'nobody' is conveniently ignoring for example these two messages: http://lists.w3.org/Archives/Public/public-html/2008Apr/0273.html http://lists.w3.org/Archives/Public/public-html/2008Apr/0322.html In summary: Requiring alt to have a value when a proper value is not available leads to developers of HTML generators to put junk into the alt value when a proper value *is not available* to the software. Putting junk there is information loss compared to signaling the unavailability. Information loss is bad, because then UAs have less information to work with in order to function to the benefit of users. To avoid this badness, alt must be allowed to be absent when the piece of software that would generate it doesn't have the data that it should put there. (Insisting that a page not be generated at all when alternative text is not available is not realistic.) > Not changes from the HTML5 baseline, but changes from the testable > assertions that accessibility checkers as implemented now are coded > to check. That's what needs to bear the burden of proof. HTML 5 is not normative over products that purport to check documents for accessibility. Those products may check for assertions that aren't part of the syntax constraints of HTML5. (However, if those tools are used for mere badge hunting, they will induce bogus alt, too.) HTML 5 is normative over what byte streams are valid HTML5. This discussion is about whether a particular simplistic purported accessibility check should be baked into the concept of syntactic correctness of the HTML5 language. > Although user issues are to be given some preference over toolsmith > issues, the accessibility checker tools are still bona-fide > stakeholders. They aren't stakeholders here. HTML5 validators are. > So the previous input concluded that the draft should be fixed to > _keep_ it required until an alternate plan for providing the > information > required by WCAG is available, The whole point is that there are HTML generators that *do not have* the information that would be needed to generate a WCAG-compliant page because someone else did not provide it. Why require the impossible (generating a page with information that doesn't exist to the generator software)? Why not admit that HTML *syntax* and accessibility are different things and that some generators at least under some circumstances produce HTML that is syntactically correct (i.e. no typos in markup) but is not accessible for everyone? -- Henri Sivonen hsivonen@iki.fi http://hsivonen.iki.fi/
Received on Monday, 14 April 2008 13:09:32 UTC