[whatwg] Early feedback on header association algorithm

Henri Sivonen hsivonen at iki.fi
Sat Nov 22 06:06:41 PST 2008

On Nov 22, 2008, at 15:50, Henri Sivonen wrote:

> On Oct 29, 2008, at 19:43, Aaron Leventhal wrote:
>> 1. On this part:
>>       "If there is a header cell in the table <http://www.whatwg.org/specs/web-apps/current-work/multipage/tabular-data.html#concept-table 
>> > whose corresponding |th <http://www.whatwg.org/specs/web-apps/current-work/multipage/tabular-data.html#the-th-element 
>> >| element has an ID that is equal to the value of id, then assign  
>> the first such header cell in tree order to the data cell. "
>> I don't want to implement a special local table only  
>> getElementByIdInTable. I'd rather have this reworded to something  
>> like
>> "If there is an element in the document with a corresponding ID  
>> (via getElementById) equal to the value of /id/, and it is a header  
>> cell in the current table, then assign it to the data cell."
> While implementing a special lookup method is something that one  
> would want to avoid, using getElementById has two problems:
> 1) It makes the association brittle under copy and paste. Consider a  
> case where a page author creates a table with internal id references  
> and then a maintainer duplicates the table and edits the contents of  
> the copy table. Now the table coming later in the document order is  
> inaccessible but this brokenness is unobvious to a person who isn't  
> accessing the page with AT.
> 2) It makes the reporting of table relationships not form a coherent  
> table. Consider a program that instead of allowing the user to  
> traverse the table an arc at a time tries to pull all the arcs from  
> the accessibility API and reconstruct the table in its own process  
> space. If there are arcs between tables, the result is not a table  
> structure at all.

Oops. I didn't read the text I quoted properly. Sorry. #2 was already  
dealt with.

However, wouldn't testing if the cell is in the current table already  
go a long way towards the complexity of implementing  

Henri Sivonen
hsivonen at iki.fi

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