- From: James Craig <jcraig@apple.com>
- Date: Fri, 21 Feb 2014 10:29:36 -0800
- To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
- Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
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 <xn--mlform-iua@xn--mlform-iua.no> 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 18:30:44 UTC