Re: Do you or Dont you buy Tim Bray's Namespace Validation Algorithm?

John Cowan (cowan@locke.ccil.org)
Thu, 10 Sep 1998 16:47:07 -0400


Mark Tucker wrote:

> DO YOU OR DONT YOU BUY TIM BRAY'S ALGORITHM for
> DTD validation in the face of Namespaces:

On reflection, I don't --- quite.

> 4. Do the same to the DTD's that you read in.

This is the sticky bit. Tim Bray phrases it as "If necessary, rewrite
the DTD so that the same URIs have the same prefixes in DTD and
instance."

However, there is no formal way to express what prefixes in the DTD
refer to what namespace URIs. In essence, you must know that in
advance. For validation to be a mechanical process, you must have
some way of recording the frozen namespace-URI map for the DTD.

(Please don't mutter "PI". That is what the old draft had, and a good
thing it was too, but the new draft abandoned it.)

-- 
John Cowan	http://www.ccil.org/~cowan		cowan@ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)