- From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
- Date: Fri, 21 Feb 2014 22:19:31 +0100
- To: James Craig <jcraig@apple.com>
- Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
Thanks, looks really promising! Leif Halvard Silli James Craig, Fri, 21 Feb 2014 10:29:36 -0800: > Just copy what the open source browsers are doing already. For example: > > AccessibilityTable::isDataTable() > http://trac.webkit.org/browser/trunk/Source/WebCore/accessibility/AccessibilityTable.cpp#L93 > > > On Feb 21, 2014, at 2:19 AM, Leif Halvard Silli wrote: > >> After filing bug 24679 [1], which suggests to add more features to the >> list of ”possible indicators”[2] for layout tables vs non-layout >> tables, I was asked to provide data for the proposals. But how should >> one go about providing data? >> >> Web data is of what ultimately matters. But when identifying possible >> indicators, it seems that knowing what features AT actually use for >> discerning between layout and non-layout tables, would give us a good >> shortlist of candidate indicators. Secondly, if we can spot some trends >> in the (hopefully correct) data we already have, then that - as well - >> could help us identify candidates. >> >> Today, its appears possible to glean following trends in the spec: >> >> 1) Conformance, completeness amd semantics indicate non-layout >> usage. The spec lists borders via CSS or @border=1, <th>, >> <thead>, <caption>, @headers, @scope. >> 2) Non-conforming ways to disable borders (border=0/cellspacing=0 >> cellpadding=0) plus role=presentation indicate layout usage. >> 3) @summary is ”not a good indicator” (this is probably based >> *both* on Web data *and* AT behavior analysis >> >> Trends & AT data applied to: table@border >> >> To me, HTML5’s table over “possible indicators” of (non-)layout usage, >> seems correct, but not complete. However, in bug 24678,[3] Steve asks >> for data about *one* non-layout indicator, namely border=1. But which >> data? Web data? Assistive technology data? The fact that VoiceOver + >> Safari matches spec w.r.t. borders as non-layout indication, ought to >> put it on the shortlist of non-layout features. In another, somewhat >> related, bug, Steve indicated that web data did not support that >> table@border=1 indicates data tables.[4] My own toe dipping into same >> pool told me the opposite. >> >> Trends & AT data applied to: <colgroup> with <col/> children. >> >> It seems in line with the conformance & completeness trend that >> VoiceOver+Safari treats <colgroup> with <col/> children[*] as indicator >> of non-layout usage. What do other ATs do? What does Web data say? >> Should the spec change accordingly? (PS: I know one HTML generator >> which, for layout tables in XHTML1/HTML4, uses cellpadding=0 >> cellspacing=0, but which for HTML5 removes cellpadding/cellspacing and >> *adds* <colgroup> with children, with bad results in VoiceOver as >> result.) >> >> Trends & AT data applied to: lack of cellpadding=0 cellspacing=0[*] >> >> Is it risky to delete cellpadding=0 cellspacing=0 from a table? >> Could it cause an AT to treat a layout table, as a non-layout table? >> This question seems relevant since authors are probably simply deleting >> these attributes without adding @role=presentation in their place. >> >> Trends & AT data applied to: presence of sortable attribute >> >> This is good candidate based on its strong link to data tables - it is >> a semantic feature. But is is also possible to take the view that we >> need implementation and usage before putting into the spec. >> >> Finally: How important are heuristics for identifying data tables? Does >> the situation remind about how UAs detect quirks vs no-quirks? (Except >> in XHTML and @srcdocs (other exceptions?), no-quirks is triggered when >> UAs detect a DOCTYPE that meets certain conformance and completeness >> criteria.) >> >> [1] https://www.w3.org/Bugs/Public/show_bug.cgi?id=24679 >> [2] >> http://www.w3.org/html/wg/drafts/html/master/tabular-data.html#the-table-element >> [3] https://www.w3.org/Bugs/Public/show_bug.cgi?id=24678 >> [4] https://www.w3.org/Bugs/Public/show_bug.cgi?id=24647#c7 >> [*] I did not check omitting <col/> child or omitting parent <colgroup> >> -- >> leif halvard silli > >
Received on Friday, 21 February 2014 21:20:01 UTC