Layers, again (was Re: fixing (just) namespaces and validation)

David Megginson david at
Wed Sep 8 22:54:00 BST 1999

Simon St.Laurent writes:

 > No.  I want to take a very well understood technology that's in the
 > XML 1.0 layer and apply it to the results of the Namespaces layer.
 > Adding qualified names processing to XML DTD validation is not very
 > difficult (as james anderson has pointed out several times on
 > another thread).

It's fairly simple to add it to the spec, but very hard to retrofit
deployed software to use it.  It is not a good idea (or good
publicity) to have two different XML dialects floating around the Web
at the same time (see further, below).

 > If there _were_ tools of any kind for processing the Namespaces
 > layer, I would be more inclined to agree with this analogy.  As it
 > stands, I'd prefer a screwdriver with a blunt piece of metal on the
 > end of the handle to nothing, thanks.

Does DDML handle Namespaces?  If so, then there's your spec.  There's
no law that says you have to wait for the W3C to bless something, and
DDML has the (good) characteristic of not breaking existing XML tools,
a characteristic missing from any modification of DTD syntax.

 > There were warnings in the XML 1.0 spec about the use of colons and
 > their reserved nature.


There was no warning, however, that DTD syntax might change.

 > I don't buy the lines you draw between the layers - I don't find them
 > logical. If you don't like DTDs and don't want to see their use extended,
 > fine.  I find your refusal to consider them a useful tool outside of their
 > original context extraordinarily puzzling.

See above.  We talked about pre-release pragmatism during the XHTML
discussion -- keep everything small, simple, and modular -- but we
also have to consider post-release pragmatism -- don't screw around
with released specs until you have a very good,
world-is-about-to-blow-up reason.  This is more of a
my-car-radio-is-stuck-on-AM reason.

All the best,


David Megginson                 david at

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