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Re: Question about ambiguous scope

From: Shadi Abou-Zahra <shadi@w3.org>
Date: Mon, 19 May 2014 18:29:41 +0200
Message-ID: <537A3175.5090704@w3.org>
To: Wayne E Dick <wayneedick@gmail.com>, w3c-wai-eo@w3.org
On 19.5.2014 18:09, Wayne E Dick wrote:
> I actually looked in HTML 4 and HTML 5 and the upper left cell is
> ambigous.  Since the next section is irregular tables, a brief
> transition from simple tables to might simply explain the upper left
> corner problem:
> Something like:
> "You may wonder whether the <th> cell in the upper left corner is
> interpreted as a row header or a column header.  It could be both.  The
> answer is that the situation is ambiguous without using the "scope"
> attribute of the <th> element. The next section on irregular tables will
> cover how we resolve the upper left corner problem and other unusual
> configurations using the attributes of <th> cells.

Could be a brief note if it doesn't add too much clutter or complexity - 
I've not encountered too many people wondering about this issue :)


> Wayne
> On 5/19/2014 1:48 AM, Bim Egan wrote:
>> Hi Wayne,
>> No, there's no de facto rule to say what direction the header in the top
>> left corner covers. It is both directions equally.  To my mind this means
>> that most tables should use the scope   attribute to ensure that screen
>> readers are given the requisite information.  However in practice this
>> isn't
>> going to happen, and while I'm fairly sick of hearing "January December"
>> when moving into the last column  of a calendar, in most cases the human
>> will either be able to determine or guess why this happens and not
>> believe
>> that January is the header for the December cell.  When headers are less
>> predictable though, it can be a real issue.
>> Cheers,
>> Bim
>>        -----Original Message-----
>>        From: Wayne E Dick [mailto:wayneedick@gmail.com]
>>        Sent: 17 May 2014 01:28
>>        To: w3c-wai-eo@w3.org
>>        Subject: Question about ambiguous scope
>>        Is the scope of upper left corner of a table ever
>>        unambiguous without a scope attribute? How does a program
>>        determine the scope upper left corner in any simple table
>>        without a scope attribute?  Are there an HTML semantic
>>        rules that says it is column or row header?
>>        Wow, I never thought about this until this morning.  What
>>        a nifty paradox.

Shadi Abou-Zahra - http://www.w3.org/People/shadi/
Activity Lead, W3C/WAI International Program Office
Evaluation and Repair Tools Working Group (ERT WG)
Research and Development Working Group (RDWG)
Received on Monday, 19 May 2014 16:30:13 UTC

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