- From: L. David Baron <dbaron@dbaron.org>
- Date: Mon, 6 Apr 2009 11:21:21 -0700
- To: public-pfwg-comments@w3.org
What follows are comments on a few parts of http://www.w3.org/TR/2009/WD-wai-aria-20090224/ . Sorry for missing the last call deadline; I only heard about the last call when the CSS group was asked to review the document last Wednesday (April 1). (These comments, however, are my own. I'm just saying how I heard about the last call.) 1.1. Scope says: # The goals of this specification include: # * defining what information may be controlled by the author; # * supporting device independence for new devices such as # telephones, PDAs, and televisions; # [...] The first of these points seems extremely broad; it should probably be scoped further. Furthermore, it is unclear to me how the specification addresses the second. My biggest concern with section 6 (Implementation in Host Languages) is somewhat broader rather than about particular pieces of text. I think the WAI-ARIA specification should encourage its own syntactic obsolescence (which I distinguish from semantic obsolescence). By this, I mean that I think the syntax described in the specification ought to be temporary, only until markup languages such as HTML define vocabularies that can be mapped into the breadth of the semantics in the WAI-ARIA specification (and are mapped that way by default). Having semantic markup for these things that is not specific to assistive technology will lead to benefits for users, including accessibility benefits. For example, in Firefox, users who have configured a Windows high contrast theme get by default the Firefox preference to ignore colors specified by the author. This preference causes problems with some types of markup where authors construct their own controls -- the same types of markup that ARIA is trying to make more accessible. For example, with this preference set, users are unable to see the selection in a tree control, since that selection is expressed as an author-specified color. The ARIA annotations don't help here, but if the tree control were marked up as an HTML5 tree control, there would be an appropriate default color for the selected row. More generally, semantic markup tends to be more accurate when it causes more effects. (This is the problem of hidden metadata tending to become inaccurate.) ARIA is somewhat self-limiting because the markup is "hidden" to anybody not using assistive technology. However, in many cases, the markup would be useful to others if it were not limited; thus I think the specification should encourage host languages to obsolete the ARIA specification by having semantic markup that, by default, covers the semantic range covered by the ARIA markup (but applies to more than just assistive technology). It might help encourage this if the specification explicitly encouraged host languages to define mappings from their markup semantics to default values for ARIA semantics. This makes me wonder whether section 6.1.4, which says, in full: # If the host language incorporates ARIA support and there is a # conflict between a host language feature and an ARIA feature, # assistive technology should assign preference to the ARIA # feature. is really the right way to go. However, I suppose it's a SHOULD-level requirement, so that if the Web evolves such that assistive technology implementers find they get a better user experience from making the opposite choice, they ought to. However, I wonder whether the specification should really even have a SHOULD-level requirement for what ought to be governed by trying to give users the best experience. (However, I concede that having this SHOULD may behavior more predictable to authors.) I'm also a bit puzzled by section 6.1.3 (Focus Navigation). It seems like it might be in the spec not because it fits with the rest of the spec, but because it's something that the spec's authors would like to enforce on other languages. That said, I think it doesn't make sense, because it doesn't necessarily make sense for *any* element to be focusable (consider elements inside the head element in HTML), and because languages might want to limit extensibility to certain elements rather than allowing all elements to be used to build controls like those ARIA is intended to provide information about. -David -- L. David Baron http://dbaron.org/ Mozilla Corporation http://www.mozilla.com/
Received on Monday, 6 April 2009 18:21:59 UTC