XHTML and the Three Namespaces

David Brownell david-b at pacbell.net
Thu Sep 23 20:08:54 BST 1999

Andrew Layman wrote:
> Here is my understanding of the XHTML namespace problem and its proposed
> solution:
> There is a vocabulary and syntax called "Strict". There is another called
> "Transitional", ...

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).

Separating those is a big part of what makes the web "Open".

> The actual difference between the elements is not sustantially their
> meaning, but only their content models and attribute lists.

Or as many people have put it, the difference isn't in the namespace; it
is instead that there are different DTDs, different syntax constraints.

> Are three namespaces the right answer?  Here is a provisional phrasing of
> the problem we need to solve: How can we reliably distinguish elements
> requiring slightly different processing, while at the same time permitting
> them to be processed similarly to the degree that the differences do not
> matter?

The simplest method remains the only one that's now standardized:  use
validation against the relevant DTD.  Processors can certainly reject
documents whose DTDs have public IDs they don't want to deal with -- maybe
they only handle the "strict" subset for some reason, so they might want to
reject documents that instead only have "frameset" grammar restrictions.

> So our present difficulty appears to be a timing problem: the three
> namespaces distinguish the different validation rules of the three
> categories of elements, but there is at present no machine-readable way to
> express their relationship. 

That's not an accurate statement.  There at present IS (!) a machine-readable
way to represent the relationship, based on DTDs and validation.  You just
appear not to want to use or discuss it.

> Of the alternatives that I have seen, only the proposal for three distinct
> namespaces seems to have sufficient information in it.  Perhaps I have
> overlooked a proposal that also works, but at this point I conclude that the
> burden of proof should rest with those who assert that the three namespace
> approach is faulty, and any such proof should include a demonstration of a
> workable, better alternative approach that actually solves the same problem.

Odd -- such demonstrations have been around for some time, suitable for use
with XHTML.  You've clearly been overlooking them, and tryied to change the
grounds of the debate to motivate a dependence on future schema technologies,
which makes many people uncomfortable because it's not known or standard.

Given that such proof has existed for some time, it still seems to me that
the burden of proof remains on those who assert a need for three namespaces.

- Dave

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)

More information about the Xml-dev mailing list