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Re: what is dt?

From: Shelley Powers <shelleyp@burningbird.net>
Date: Thu, 17 Sep 2009 12:32:53 -0500
Message-ID: <4AB272C5.4040802@burningbird.net>
To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
CC: public-html@w3.org
Leif Halvard Silli wrote:
> Smylers On 09-09-17 18.18:
>> Shelley Powers writes:
>>> Smylers wrote:
>>> Except now, when seemingly dt and dd have become HTML5 silly putty:
>>> good for a hundred and one uses.
>> So it's actually <dl>, <details>, and <figure> which have different
>> uses.  <dt> and <dd> are 'building blocks' which each of those happen to
>> contain.
> Agree in principle about 'building blocks'. <li> is also the building 
> block of both <ul> and <ol>.

But the li element is used exactly the same in ul and ol. The same does 
_not_ apply to dt/dd in Figure, Details, and dl.

There is no confusion about what is the allowable usage of li in ol, as 
compared to allowable usage of li in ul. How one lays out one's items 
differs, but the syntax is exactly the same. Even the semantics is the 
same: li is a list item, period. One can view source an see how li is 
used in ol, and use the same syntax in li. The ol and ul elements may 
differ, but the use of li is the same.

(Of course now we have menu, but again, the use of li remains exactly 
the same. )

Look at the syntax for dt now:

Before dd or dt elements inside dl elements.
In a figure element containing no other dt element children.
As the first child of a details element.

One could look at how dt is used within dl, and extrapolate from that 
usage, how the dt element could be used in Figure. Except for one thing: 
it would be wrong. In fact, extremely wrong. There are significant 
differences to how dt/dd are syntactically used in all three of the 
elements. I'm not talking about minor differences in semantics and 
syntax, I'm talking about completely and absolutely different.

What happened is people searched for a set of constraints based on 
legacy browser physical behavior and just grabbed whatever made it 
through the filter. The confusion caused to existing web developers and 
designers, as well as new web page authors in the future was, from what 
I can tell, never once factored into the decision.

>> And they hardly have completely different uses: in all cases the <dt> is
>> being used to label the <dd>, so they're comparable (in a way which,
>> say, using the same element for each of <meta>, <li>, and <tbody> would
>> not be).
>> <dt> is an awful name for an element which means 'figure caption'.
>> Indeed it's hard to think of anything which could be a worse name.  But
>> it isn't entirely inconsistent with other uses of <dt>.
> Do we need to call it a caption? Could we not say "description"?
> The draft sees <dl> as a "description list", with <dd> as the 
> description of the <dt>. However, inside <figure> the <dt> becomes the 
> description of the <dd> ...
> If we instead consider <dl> - still - a "definition list", then it 
> becomes clearer ...

Someone once said to think of dt/dd as a keyword/value pair, except that 
syntactically, this doesn't match how they are used in all three elements.

We can rename things all we want, the issue still remains: the 
differences in semantics and syntax are significant enough that they 
will, most likely, cause significant problems in their usage in the future.

Received on Thursday, 17 September 2009 17:33:38 UTC

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