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Re: Proposed: a TN tag to join TH and TD?

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From: Duff Johnson
Date: Jun 11, 2013 7:39AM

Thanks for the input! Very interesting…

>> One solution we are thinking about is a new cell type to join TH and
>> TD. We're thinking it's called TN, for "no-op".
>
> You would need to define the meaning differently, in more structural, or
> "semantic" terms.

A TN cell is to be represented as "Intentionally blank".

> Moreover, it's not clear that a new tag would be the
> best approach, especially since we don't want old software to choke with
> a document just because we have improved its tagging.

A very valid point… and yet, we're trying to look (for now) at "how should it be done" rather than simply caving to the dead weight of old software. ;)

> In HTML at least,
> I would strongly recommend proposing a new attribute rather than a new
> element. This would let browsers keep doing what they are doing now,
> just ignoring the attribute. In HTML5, it could be a "boolean" attribute
> (a pure keyword attribute), e.g. <td dummy> or <th dummy>.

I have previously made this suggestion myself in internal discussions on this point. The objection was that unlike TH and TD, TN never, on principle, contains real content, and so genuinely isn't the same sort of animal as TH or TD.

>> The most common use of TN would be at the empty "corner" of a table
>> (a very common case) or (less commonly) in the middle of a TH row or
>> column, or where one might otherwise expect a <TD> cells filling a
>> gap.
>
> The first case is clear and can easily be explained and defined. There
> would be a cell in a table such that other cells in the same row are
> column headers and other cells in the column are row headers, leaving no
> choice for this cell to be anything but a filler, required to make the
> table regular.

Precisely so.

> On the other hand, in HTML, such a situation could be recognized from
> other markup if scope attributes are used for those other cells.

Well, that's sort of my question, because it seems likely to me that, in point of fact, scope doesn't help.

In the attached screen-shot a table is indicated in which a single cell in the leftmost column of row-headers was "intentionally left blank." I'm not sure how to treat this with existing markup and remain unambiguous.



> But what other cases would there be? I would propose starting with the
> hypothesis that all other cases can be handled as normal cells with some
> logical content that may physically be displayed and spoken as blank but
> isn't really comparable to the dummy cells. On my page about empty cells
> in HTML, I suggest various ways to make cells not empty in data content
> even though they lack normal data:
> http://www.cs.tut.fi/~jkorpela/html/emptycells.html

THanks for the link - excellent article!

Yes, the "CSS way" (from your article) is interesting in this regard. Of course, in PDF we have no CSS...
>
> So I would say that as a rule of thumb, when a table cell would be empty
> due to lack of data or because data is not relevant, it should be marked
> up as a normal cell, and we should consider whether some character data
> should still appear in it.

Agreed - that's a distinct use-case - not the one I was positing.

> And really dummy cells are probably a special
> case that can be handled with existing markup or that does not need any
> particular handling.

Well, that's what I'm wondering.

- Yes, they are a "special" case, but also a common case.
- It seems they need markup, otherwise (in the case of TH rows and columns) users must be left wondering which TH cells are headers for the TDs that have (nominally) a "dummy" TH as their row/column headers….

It's more likely, of course, that I'm either missing something or making a mountain from a mole-hill...

Duff.