[whatwg] Table integrity and conformance

Ian Hickson ian at hixie.ch
Mon Oct 23 11:31:30 PDT 2006

On Mon, 23 Oct 2006, Henri Sivonen wrote:
> > 
> > Should one expect HTML table row/column integrity to become an HTML5 
> > conformance requirement?
> I'd appreciate some indication on what I should expect in this area, 
> i.e. whether it makes sense to prototype a table integrity checker based 
> on HTML 4 forms.

I'm not planning on actually speccing tables for a while (but maybe I'll 
get to it by the end of the year), which is why I haven't replied to your 
last e-mail yet.

I think it would be good to require table integrity. Specifically I think 
overlapping cells would be a MUST NOT. I don't think there's a problem 
with missing table cells at the end of rows (i.e. a ragged table is fine). 
I think cells extending (via colspan/rowspan) into columns or rows that 
contain no cells other than extended cells should be at least a SHOULD 
NOT, maybe a MUST NOT.

I don't know whether we'll keep the requirement that TFOOTs be above 
TBODYs. COLGROUP span="" will be illegal if the COLGROUP has COLs. COLs 
and COLGROUPs will probably have a SHOULD NOT requirement about spanning 
into columns with no actual cells.

And the SHOULD NOTs will probably be MUST NOTs.

headers="" will have a MUST requirement to point to TH elements in the 
same table, and will probably only be allowed on TDs. scope="" will 
probably only be allowed for THs. Maybe it should be REQUIRED for THs that 
aren't in obvious locations (first row, first column, or whatever).

It might be interesting to have some sort of testing with the "axis" 
attribute too, or maybe we should drop it. (Indeed maybe we should drop 
some of the others, too.)

If you do do this, I expect your experience with writing the conformance 
checker will be a large influence on what the spec end up saying.

On a related note, a potentially interesting feature of a conformance 
checker would be to output the document outline so that a human can check 
that that is correct.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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