Another look at namespaces

David Megginson david at
Thu Sep 16 01:29:09 BST 1999

[I'd like to start by thanking Tim for making his personal views known 
in a public forum.]

Tim Berners-Lee writes:

 > What happens when a version one program meets a version 2 document?

As Tim points out, this is (or at least, should be)
application-specific.  I have omitted his summary, but I agree with
its broad outlines.

Unfortunately, I think that Tim B-L and Paul Prescod are wasting a
little of their typing preaching to the converted; we all (or at
least, most of us) agree and always have agreed that the following are
basic requirements for dealing with Namespaces:

1. An application must be able to determine the general language used
   by (part of) a document.
2. An application must be able to determine the specific dialect used
   by (part of) a document.
3. An application must be able to locate schemas, stylesheets, and
   other materials related to a language (or dialect).

What is contentious is not whether these three requirements are real,
but rather, what mechanisms for satisfying them will be most likely to 
gain acceptance and what mechanisms will work best in Web environment.

The guiding design principle should be to make the most
commonly-needed information the most accessible.  I believe that

a. the vast majority of applications will be most concerned with #1;
b. the applications concerned only with #1 will tend to be the
   lightest-weight ones.

If my guesses are correct, then it is essential that the answer to #1
be trivially obtainable -- in the document, through the Namespace URI
itself -- while the answers to #2 and #3 can be made available through
secondary mechanisms such as conventional Namespace attributes (such
as 'version') or packaging manifests.

We mustn't make easy tasks difficult for the sake of theoretical
purity -- I know, because we tried to do that over and over again in
the SGML world, and, well, we're not debating SGML any more, are we?

All the best,


David Megginson                 david at

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

More information about the Xml-dev mailing list