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- From: len bullard <email@example.com>
- To: firstname.lastname@example.org
- Date: Thu, 23 Apr 1998 18:40:14 -0500
Tim Bray wrote:
> At 01:15 PM 4/23/98 -0400, Paul Prescod wrote:
> >If XML had no semantics, then XSL, XLL and the DOM would have to
> >explicitly describe the mapping from syntactic features to the abstract
> >nodes that they work on. But they do not, because XML has semantic
> >concepts like "element, "element type", "notation" and "attribute" that
> >are *described by* the syntax.
> Well, we just have a difference of perception.
> Dan Connolly has argued repeatedly and forcefully that
> the spec could be completely re-written to avoid discussion of the
> processor's actions (he is right) and that this would be an improvement
> (I'm not convinced).
That a spec can be rewritten to to exclude information of
use is not arguable. Yet contextually, the project was/is
SGML On The WEB. There are two main requirements in that
a. SGML (done)
b. On The Web. b is a systemic requirement.
Systemic requirements require semantic information. Removing
those from the spec unlimits the spec, but I think makes them
much less useful. Failure to do this for SGML systems
made SGML less useful, and arguably, less attractive
to implement. Why? Friendly to Information Maintenance but not
very good for system interoperability. The industry did not
get enough cohesion among systems to get community reinforced
growth. No amplification.
It depends on what one needs to improve. One
can get hung up on information purity issues and not see
the systemic problems of a standard framework. Isn't avoiding
that mistake precisely what made HTML/HTTP work?
> The fact that the XML processor has a couple of required *behaviors*,
> most notably error handling, does not constitute anything like
> what I think of in connection with the term "semantic".
They are semantics/behaviors defined to make them useful.
> But in the instance, Elements and attributes don't mean anything in and
> of themselves. They doubtless have semantics that are used by humans and
> computer programs in particular application domains, but that's none of
> our business.
Yes they do. They are meant to readable to humans and machines. This
is a contractual semantic. The meaning is in the intent of the design.
Say 'does this' and the semantic is there in the requirement.
> And finally... words are only of use in facilitating human
> communication when there is some shared understanding as to their
> denotation and connotation. The term "semantic", judged by this standard,
> has clearly and empirically lost its usefulness in this discussion.
Hmmm... no. But the semantics of markup systems (not markup) are
limited to the agreed upon meanings. You have contractual semantics
(design requirements) and systemic semantics (environment where
requirements are testable).
> But of this I am confident: elements, attributes, and entities don't
> mean anything in and of themselves. -Tim
They mean what we agree to make them mean. Right now, we agree
to make them readable to human systems and machine systems.
XML is a system-centric standard. SGML is not. XSL,
DOM, XLL are system applications. This does not mean they
will not meet the loftier goals of information evolution,
but they have to operate to do that.
The pursuit of meaning is a human pursuit. Machines, like XML,
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