Re: Generic Markup [was:Re: deprecated tags in Wilbur & Cougar]

Marc Salomon (marc@ckm.ucsf.edu)
Fri, 9 Aug 1996 16:35:32 -0700


From: "Marc Salomon" <marc@ckm.ucsf.edu>
Message-Id: <9608091635.ZM7630@gaia.ckm.ucsf.edu>
Date: Fri, 9 Aug 1996 16:35:32 -0700
In-Reply-To: Gavin Nicol <gtn@ebt.com>
To: www-style@w3.org, www-html@w3.org
Subject: Re: Generic Markup [was:Re: deprecated tags in Wilbur & Cougar]

Gavin Nicol <gtn@ebt.com> wrote:
|If they can parse HTML and derive structure from attribute values, and
|actually make use of that structure, they can do the same for GI's.

But not if those GI's don't yet exist.  There seems more intertia towards
standardizing on CLASSES than on a set of GI's.

|In fact, for indexing purposes, you'd probably get better indexes built
|(you can search by containment and attribute values).

Yes, Yes, Yes, Yes and YES.  I don't think GI's are a Bad Thing at all.
 They're just not here now, since they're not here, they're not standardized
either, while the CLASS mechanism is on its way and will blur the distinction
between pres and struct.

Look, I don't see using attributes to express structure as anything but a
bridge technology towards a "real" SGML future.  I want to encourage/enforce
the separation of structure from presentation as much as is feasible.  But
until there are mature proposals for using GI's to interoperably express
structure on the WWW, I am concerned to see CLASS, as specified in Cougar, used
or at least intrepreted for both, as harmful towards continuing that
separation.

On a quick evaluation of the TEI DTD, they seem to take (for the default case)
the attribute-as-structure approach on their generic <DIV*> elements, although
a customization/extension mechanism exists.  Their approach separates
presentation from structure exactly as I'm suggesting by dividing that work
between the TYPE and REND attributes.

|I should note that your question is actually fundamentally deeper than
|just HTML. The problem of DTD equivalency is a very difficult one,
|though architectural forms can help.

This is clearly a question for further reasearch and should not stop efforts to
inflate the flatness of the HTML DTD over the near term.

|>|How many attributes did you propose?
|>
|>The debate earlier on STYLE attributes proposed one.  CLASS proposed a
second.
|>Both of these attributes are included in the Cougar DTD.  ROLE that I propose
|>would be a third.
|
|Your example used COLOR...

It used (or was supposed to :) be something in the form of:

<SPAN STYLE="CSS: color=blue_in_the_face">...</SPAN>

That hid the nastiness in an attribute.

|In both cases, I cannot see why anything that can actually *use* the
|structure shown by the CLASS attribute for anything beyond style
|selection, cannot also use a form that uses GI's.

Because the choice has been made, for the sake of mass consumption
generalization,  to keep HTML simple.  I see a clear path towards your more
ideal but not yet mature solution in standardizing on a small set of structural
attributes aside from presentation classes and then fleshing out the problems
involved in establishing equivalencies between arbitrary tagsets.

I don't see many GUI clients making use of a structural attributes, just as I
don't see many robot indexers making use of presentation classes contained in
attributes.  As the Cougar effort stands now, GUI browsers win at the expense
of smart robot indexers.

But the real conflict comes in that browsers are supposed to be liberal in what
they accept, rendering any tagset that isn't catestrophically broken.  But  the
value of producing conforming HTML documents is common wisdom not to be
questioned.

Do you claim that validation is only needed to know about omittag?  How are we
to resolve this dissonance in philosophies (or at least common wisdoms)?  And
are is it practical at this time to propose a global registry (yet another
registry) of GI equivalency mapping tables?

-marc

--