[html4all] Headers= up

Fri Sep 7 21:36:23 PDT 2007

Hi Leif,

On close examination I think the HTML 4.01 algorithm should work  
perfectly with Anne's table with no scope attribute. James'  
implementation simply implements it incorrectly.

The HTML 4.01 algorithm says:

"The search in a given direction stops when the edge of the table is  
reached or when a data cell is found after a header cell."

So the HTML 4 algorithm should not be including the Day 1, Day 2,,  
Day3, etc. headers. Though in fairness it also should not include the  
remarks and the other header cell in the THEAD< but I think that a  
generous reading of HTML4 would include those headers.

Take care,
Rob

On Sep 7, 2007, at 11:15 PM, Robert Burns wrote:

> Hi Leif,
>
> From a cursory glance at these, they do not seem to me to implement  
> the algorithms as listed in the respective recommendations. That's  
> not really that important, but it does seem to be constructed to  
> make the HTML4 algorithm look inadequate and the HTML5 algorithm to  
> look like the savior here. The short-coming of the HTML 4.01  
> algorithm is that its not explicit enough [1]. However, that  
> doesn't mean it should be interpreted in silly sorts of ways.  The  
> HTML5 algorithm is, in contrast, very explicit and, as such is also  
> inadequate.
>
> The goal for the HTML WG is simply to find an algorithm that works  
> well in the absence of explicit 'headers' attributes regardless of  
> whether that draws on HTML 4.01 or the current draft. However, the  
> problem now is that James's implementation of the HTML5 algorithm  
> glosses over its deficiencies to make it look like its adequate  
> already [2].
>
> The HTML4 algorithm is actually quite short and quite easy to  
> follow. James interpretation looks way off to me, but that's not  
> really that important. It's the interpretation of the HTML5  
> algorithm that tries to make it look like we have an adequate  
> algorithm that's the problem.  In the absence of scope (if we take  
> this literally) the header cell is actually supposed to be assigned  
> to every data cell (which basically renders the header cells  
> useless). The HTML5 algorithm says that
>
> "If the header cell is not in the first row of the table, or not in  
> the first cell of a row, then don't assign the header cell to any  
> data cells."
>
> Anyway, I think at this stage we should largely throw out the  
> different algorithms (and especially comparisons of the different  
> algorithms ) and work towards refining an algorithm that works  
> well. We should also be clear that the James implementation of the  
> HTML5 algorithm does not reflect the current draft, otherwise we'll  
> be lulled into thinking the current draft is adequate.
>
> To get an algorithm that works well I think we also need to rethink  
> the 'scope' attribute. Right now it has the values: 'col',  
> 'colgroup', 'row' and 'rowgroup'. However this is confusing because  
> a column heading will typically either have a 'col' value or a  
> 'rowgroup' value, so the meaning or 'row' and 'rowgroup' actually  
> have no relation. I think the HTML4.01 approach is better in that a  
> corner header cell may apply either to the column or the row or  
> both. Row group and column group just add to the confusion. So  
> here's how I think the algorithm should be constructed:
>
>  • header cells in the thead (or even all cells in the thead)  
> should apply to all cells that they column span
>  • header cells in a tbody should apply to all remaining data cells  
> beneath them that the header cell colspans and all remaining data  
> cells to the right of them (left of them for dir=rtl) that the  
> header cell rowspans subject to the following qualifications
>     - whenever a run of data cells reaches another header cell the  
> association should stop
>     - to associate header cells (and therefore the data cells that  
> they associate with) with other header cells the headers attribute  
> should be used. This would for example accomplish the same thing  
> for rows that can be accomplished without headers= for columns  
> using the thead element. For example if an author includes a column  
> of row header cells at the beginning of a table and then includes  
> several other columns of row header cells that will apply only to  
> data cells in the rows locally according to this algorithm, the the  
> use of headers='' will allow associating different groups of data  
> cells and control scoping better and more clearly.
>     - scope of 'col' limits that to only the cells beneath them and
>     - scope of 'row' limits that to only cells to the right of them  
> (left of them for dir=rtl).
>     - the rowgroup and colgroup values for scope should be  
> eliminated except for legacy reasons. They create confusion because  
> they overlap with an author that might want to break the table into  
> arbitrary groups of data cells broken by a new band of one or more  
> consecutive header cells. If these authoring techniques are at  
> cross purposes its just more confusing for authors.
>  •  axis should be rethought because I don't think its clear enough  
> from HTML 4.01 and common usage or implementations what it means
>  • with this approach headers= would be mostly reduced to an  
> attribute on TH cells that would automatically associate the TH  
> cell  and all of its associated TD cells with another TH cell.
>
> Those are my thoughts, I support I should put something more formal  
> together, but I thought I'd see what users on this list think.
>
> Take care,
> Rob
>
> [1]: <http://www.w3.org/TR/html4/struct/tables.html#h-11.4.3>
> [2]: <http://dev.w3.org/cvsweb/~checkout~/html5/spec/Overview.html? 
> rev=1.78#header-and-data-cell-semantics>
>
> On Sep 7, 2007, at 9:23 PM, Leif Halvard Silli wrote:
>
>> Don't know what happened to my message ... something ate it.
>>
>> So I better put it short. Have a look at Ben's message to Publich  
>> HTML:
>>
>> 2007-09-07 21:13:03 +0200 "Ben 'Cerbera' Millard"
>> <cerbera at projectcerbera.com>:
>>
>> [ ... issues in Anne's web log ... ]
>>> Oh, and I'm [famous] now. :-) If you are new to the HTML5 tables
>>> effort, that
>>> blog entry from Anne is an excellent introduction, imho.
>>
>>> [famous] <http://annevankesteren.nl/2007/09/html-tables>
>>
>> And read Anne's blog. It shows some misconspetions about @SCOPE vs.
>> @headers (which I was explaining ... but he make it sound as if
>> @headers is almost against the nature of the table.)
>>
>> I recommend tryhing Anne's table [1] in the table inspector [2]. You
>> will see that if you test the table _without_ any attributes at all
>> (use the option to turn off @SCOPE and @HEADERS), then it works  
>> almost
>> the same as it does with the HTML5 algorithm _with_ the @SCOPE
>> attributes that Anne applied. (It is of course funny that one can
>> achieve the "no attributes" solution that Anne pledges for with HTML4
>> - but not in current HTML5 ... )
>>
>> Rob, or anyone, there is small difference: HTML4 without @SCOPE shows
>> more headers - but I think in this case the HTML5 show is better.
>> Agree? (Chime in, you aural browsers users!) But what I wonders  
>> about:
>> how do I make the same happen in HTML4? Hint: the challenge is the  
>> row
>> with <th colspan="4">, which makes it impossible to use headers="".
>>
>> [1] <http://annevankesteren.nl/2007/09/tmb-overview>
>> [2] <http://james.html5.org/tables/table_inspector.html>
>>
> _______________________________________________
> List_HTML4all.org mailing list
> https://www.html4all.org/wiki

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://wilbur.bytowninternet.com/pipermail/list_html4all.org/attachments/20070907/ee68116d/attachment.html 