- From: James Graham <jg307@cam.ac.uk>
- Date: Mon, 24 Mar 2008 23:48:02 +0000
- To: public-pfwg-comments@w3.org
(apologies for my earlier prematurely sent mail on this subject) The authoring requirements for aria-level seem unclear. In particular, when level is needed, or how to determine that reliably. The paragraph "In many cases the user agent may be able to calculate the level of an item if it can be determined correctly from the document structure. This property may be used to provide an explicit indication of the level if that is not possible from the document structure. User agent automatic support for automatic calculation of level may vary; it is recommended that authors test with user agents and assistive technologies to determine whether this property is needed." is somewhat bewildering as it states that in (some? many?) cases aria-level will not be needed at all, without suggesting what those cases are. The suggestion that authors determine what works using trial and error with UAs seems unhelpful; it is unlikely that authors have access to all available client software and the implicit suggestion that non-interoperability from UAs on how they extract document structure from markup seems likely to lead to user frustration as something that worked on the author's test-platform works differently for them. Suggestion: Make it a conformance requirement that aria-level not be used in situations where the UA can infer hierarchy from the document structure alone e.g. with html heading elements. This prevents problems like <h1 aria-level=2><h2 aria-level=1> where the document semantics depend on whether the client understands aria-level at all. (I also think that UA conformance requirements should prefer host-language semantics to aria semantics in case of conflict but that is a separate, more general issue) Indicate cases where it is known that aria-level is not needed because the structure can be inferred and cases where it is needed, with examples. Ensure that all cases where the UA can infer document hierarchy from structure are specified well enough that it is trivial to build interoperable implementations (this is probably mainly a host language issue, but where known host languages fail to fufill this, they should be fixed). Make it a constraint that the highest level in the hierachy has aria-level=1 and for elements at level n, children in the hierarchy have aria-level n+1.
Received on Monday, 24 March 2008 23:48:44 UTC