XHTML and the Three Namespaces

David Brownell david-b at pacbell.net
Sat Sep 25 16:35:22 BST 1999

Andrew Layman wrote:
> Regarding David Brownell's statement, "It's my understanding that the
> essence of the problem is in the assertion you made there, and throughout
> your post:  that vocabulary and syntax and namespace are one one thing,
> rather than at least two (vocabulary/namespace, and separately syntax as
> today captured in DTD)"; I do not in fact make this assertion.  What I
> said was "There is a vocabulary and syntax called 'Strict'. There is
> another called 'Transitional'..." I later stated that the solution WG
> proposed by the XHTML was to distinguish these by use of namespaces.

I can't think I'm alone in reading "a vocabulary and syntax" there as
a statement about _one_ thing, rather than at least two.  You later
wrote about "giving each of the three grammars a namespace" (closing
the loop) and said that "elements in each namespace are to be validated
against the DTD corresponding to that namespace" to drive it home.

> I work to make my wording exact.  Please read my mails as though I actually
> said what I meant.

Many of us work to write exactly what we mean, but I know of nobody that
avoids mistakes there.  For example, I'm unclear what you think I misread
in what you were writing.  In what way were you not equating those things?

Your points 1-7 come across differently, at least to me.  Re point 2,
which you identify as "the point of greatest misunderstanding", it
is enlightening in juxtaposition with point 3:

> 2.      Anything so identified can have, at most, one definition.
> 3.      All distinctions between identified items must be reflected 
>         by a difference in the respective identifiers.

Although any page of a dictionary will have multiple definitions for some
word, so I'd disagree with #2 on first principles, I think a related issue
is perhaps what is meant by a "definition" (as pointed out by Marc McDonald).
It's clear to me that #3 is equally wrong:  not all distinctions ought to be
captured in identifiers.  Context is an essential tool.

Different usage contexts may have different "definitions" that are fully
consistent.  The presentational definition of "xhtml:li" is one thing in
terms of CSS, another (related) in terms of FOs; and neither is the same
as the syntax rules saying where they may appear.  The "meaning" (and hence
definition) is a function of the task being performed.

That again argues against the possibility that there be a "definitive"
definition, accessed by retrieval through a namespace URI or encoded in
any kind of schema.

- Dave

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