704465 - any element pointed @headers attribute should be exposed as table header

Status: RESOLVED FIXED

(Core :: Disability Access APIs, defect)

Description

[alexander :surkov (:asurkov)]

spun off bug 702978 comment #2-#3.

Comment 1

[alexander :surkov (:asurkov)]

Steve, but if we are going to expose any element pointed by @headers attribute then we need to decide whether it should be exposed as column header or as row header (that APIs requires us to do). We could exposed those unmapped as relations like labelled_by but I'm not sure. Ideas?

Comment 2

[steve faulkner]

OK, I was assuming that headers references can/should only be pointing to col/row headers in the same table, as per spec:

http://dev.w3.org/html5/spec-author-view/attributes-common-to-td-and-th-elements.html#attr-tdth-headers

"The td and th element may have a headers content attribute specified. The headers attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an ID of a th element taking part in the same table as the td or th element."

Comment 4

[alexander :surkov (:asurkov)]

Note, bug 877386 has an example, testcase and some discussion.

Comment 5

[alexander :surkov (:asurkov)]

Attachment: patch

it seems the best what we can do here is summarized by bug 877386 "Table headers not associated when header is a td element with no scope"

Comment 6

[Trevor Saunders (:tbsaunde)]

Comment on attachment 757281 [details] [diff] [review]
patch

I'll never understand why html was designed this way but I guess we have to deal.

Comment 7

[James Teh [:Jamie]]

To make matters more confusing, HTML 4.01 and HTML 5 say different things about this.

HTML 4.01 says headers can point at either td or th:
> Note that it's not always possible to make a clean division of cells into headers or data. You should use the TD element for such cells together with the id or scope attributes as appropriate.
(http://www.w3.org/TR/html4/struct/tables.html#h-11.4.1)

HTML 5 (as referenced in comment 2) says headers can only point at th:
> The td and th element may have a headers content attribute specified. The headers attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an ID of a th element taking part in the same table as the td or th element.
(http://dev.w3.org/html5/spec-author-view/attributes-common-to-td-and-th-elements.html#attr-tdth-headers)

I guess we still need to support HTML 4.01. :(

Comment 8

[alexander :surkov (:asurkov)]

the example above seems valid (th has styling, td doesn't have so using td to describe other cells seems reasonable and thus it's also reasonable to expose them as headers).

Steve, you know why HTML5 doesn't allow td anymore?

Comment 9

[alexander :surkov (:asurkov)]

http://hg.mozilla.org/integration/mozilla-inbound/rev/c2c4b87b2a6f

Comment 10

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/c2c4b87b2a6f

Comment 11

[steve faulkner]

(In reply to alexander :surkov from comment #8)
> the example above seems valid (th has styling, td doesn't have so using td
> to describe other cells seems reasonable and thus it's also reasonable to
> expose them as headers).
> 
> Steve, you know why HTML5 doesn't allow td anymore?

I don't know why (wasn't my doing and can't find paper trail). My advice would be to honour the headers relationships whether they point to td or th. The forbidding of headers references being a td should only be for authors not implementers. If this is not clear in the spec [1], please file a bug [2]

[1] http://www.w3.org/html/wg/drafts/html/master/tabular-data.html#attr-tdth-headers
[2] https://www.w3.org/Bugs/Public/enter_bug.cgi?product=HTML%20WG&component=HTML5%20spec&priority=P3

Comment 12

[Hixie (not reading bugmail)]

The parts of the spec that were being cited in this bug are the wrong parts of the spec, by the way. Those are the authoring requirements. For a browser, you only want to be looking at the conformance requirements for user agents, which do require that headers="" work whether pointing to a <td> or a <th>:
http://www.whatwg.org/specs/web-apps/current-work/multipage/tabular-data.html#header-and-data-cell-semantics