Re: How namespace names might be used

At 10:58 AM 2000-06-13 -0400, W. E. Perry wrote:
>Dan Connolly wrote:
>
>> Jelks Cabaniss wrote:
>> > But ... the more fundamental question, framed even earlier by Walter
Perry[2]
>> > about the very assumption of this whole namespaces/semantics business,
has never
>> > been answered.
>>
>> There's a lot in that message. Could you state this "more fundamental"
question
>> briefly, please?
>
>I'll do it myself, if I may quote my first posting to this list (on 15
May, the first
>day of this discussion):
>
>Tim Berners-Lee wrote:
>
>> There are those who would maintain that a
>> namespace should have no semantics, but I would say that then documents
will
>> have no semantics, and will  be useless to man or machine.  [You can go
>> through the philosophical process of defining all semantics in terms of
>> syntactic operations, of course, in which case the pedant can take the view
>> that all is syntax, but it is not a helpful view when making this decision,
>> as it leaves the main points the same and just gives a more difficult
>> framework for most people to think of it].
>
>I have argued for many months (e.g.
http://xml.org/archives/xml-dev/2000/03/0380.html
>) that semantics are local to the node where instance markup is processed
and that the
>XML family of specifications could (should!) aspire to no more than the
specification
>of syntax.
>[http://lists.w3.org/Archives/Public/xml-uri/2000May/0006.html]
>
>'Namespaces in XML' chose a syntactic solution which specifically
disavowed URI
>semantics. If the present debate is, as I believed it was originally
framed, about
>whether we should re-open the Namespaces spec in order to heap greater
semantic
>expectations upon the syntax there described, then the present forum might
also
>consider the question whether, in general, prescribing specific semantic
expectations
>of any particular syntax is a good, or even a workable, approach for a
body such as
>the W3C.
>
>Respectfully,
>
>Walter Perry
>

Walter, it is not meet that semantics [even post-syntactic semantics]
should be entirely private to the node.  This leaves out too much of the
utility of communication using mutually understood encodings.

This may sound paradoxical, but in terms of the strategy of the WAI to
achieve accessible-by-construction Web content, we find that in order to
permit more latitude in the presentational semantics of shared literature
[HTTP etc. messages] it is necessary to have compensatingly better-shared
constraints across author and reader processing in cognitive-semantic
dimensions.  Sort of a Heisenberg uncertainty principle inside out.  Here
you can only tolerate so much uncertainty, so you have to be inside a
permissible-perturbation surface of fixed volume; to relax it in one
direction you have to tighten the laces in another.

In reply to Jelks's question, I thought that I had demonstrated a
requirement for semantics that could not be refused:

Two examples, in fact, where the parse tree [in a table such as in HTML or
CALS DTDs] is overloaded with secondary structures with semantic
connotations:  the table column as a collection structure, and the html:th
element type as fulfilling a metadata function as regards associated
html:td cells.

If you don't understand why the WAI cares about these semantic connections,
please review 

* the note about accessibility features of HTML at
  http://www.w3.org/WAI/References/HTML4-access

* the W3C Recommendation "Web Content Accessibility Guidelines 1.0" at
  http://www.w3.org/TR/WAI-WEBCONTENT

This is why Simon, TimBL, Tim Bray and I, each in our own words, have all
been talking up separation of concerns.  Whether you call it packaging,
layering, or architecture, there needs to be a way for syntax and semantics
to coexist in the the platform for effective communication without sending
processing into a spiral of infinite regress.

"Zero semantics" is a Solomonic judgement that this mother-claimant, at
least, wants to reject immediately.

Al

Received on Tuesday, 13 June 2000 13:30:58 UTC