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Re: XHTML 2.0 - dfn : Content model and usability (PR#7832)

From: Jukka K. Korpela <jkorpela@cs.tut.fi>
Date: Fri, 24 Mar 2006 10:24:28 +0200 (EET)
To: "'www-html@w3.org'" <www-html@w3.org>
Message-ID: <Pine.GSO.4.64.0603241003440.29477@korppi.cs.tut.fi>

On Thu, 23 Mar 2006, Rob Simpson wrote:

> Regarding the "<dfn/>" element, why is yet another "definition of term"
> element needed in HTML?

It's a holdover from HTML 3.2. It isn't even legacy markup, since it has 
been used very little; it exists in theory only.

> Wouldn't "<dl><dt
> id="def-acronym">acronym</dt></dl> the definition" suffice,

For what? What is the purpose of using definition markup? The <dl> has 
largely become a poor man's layout tool (for certain types of lists) 
rather than structural markup. Continuity with previous versions of HTML 
would be a good reason _not_ to use the same element name if you wish to 
specify an element that _really_ means a list of definitions. You don't 
want to send the message "hey, this is good old <dl> that the W3C has 
always told us to use for lists of stuff with indented description below 
each major item".

Technically, <dfn> is a standalone inline element, so it is syntactically 
rather different from <dt>.

Both <dfn> and <dl> would be worse than useless in XHTML 2.0 especially 
since they are have essentially been copied from HTML 3.2 via HTML. It's 
illogical to have markup (nominally) for a definition list without having 
markup for a definition. A single-definition <dl> would be an artificial 
approach to giving an isolated definition. Moreover, it would apply only 
to a small subset of definitions: those that are expressed as separated
into a definiendum and a definiens. The <dfn> markup is far too primitive, 
since it only says "this is a defining occurrence" (essentially, it's 
just a kind of highlighting) without specifying what constitutes the 
definition.

If you want definition markup, you need a good analysis of what 
definitions are - a  definition of "definition", really (see 
http://www.cs.tut.fi/~jkorpela/def.html for an attempt) _and_ some idea of 
how definition markup could be made popular among authors _and_ some 
support to such markup in popular software (especially browsers and 
search engines). This is really a chicken and egg problem.

-- 
Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
Received on Friday, 24 March 2006 08:24:38 GMT

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