W3C home > Mailing lists > Public > xml-uri@w3.org > May 2000

Re: Remember: namespaces break DTD's

From: David Carlisle <davidc@nag.co.uk>
Date: Mon, 22 May 2000 16:21:04 +0100 (BST)
Message-Id: <200005221521.QAA18100@nag.co.uk>
To: abrahams@acm.org
CC: xml-uri@w3.org


> My reading of the situation -- and if yours is different, I'd like to hear it
> -- is that in essence the W3C XML community sees DTD's as a historical
> anachronism.  They have to be supported because there are a lot of them
> around, but schemata are the way the future is going.  For that reason,
> people in W3C are not willing to devote any energy to repairing anything that
> might be wrong with the use of DTDs in XML, including the problems of using
> them in conjunction with namespaces.

You can use DTDs with XML namespace documents so long as you restrict
yourself to using just one prefix for each namespace within any given
document. You can't sensibly support changing prefixes on arbitrary
elements. In practice this means most documents are OK.

Doing better than that would mean breaking existing tools and breaking
SGML compatibility, and if you are going to break that much, the
benefits of keeping dtd syntax are rather slight.

Personally I don't think DTDs will go away in a hurry, although I do
have high hopes for XML schema. But having broken the mould and left
the DTD syntax I suspect that XML schema will never have the total
dominance for XML that DTD have for SGML. Once it is recognised that
different schema languages can co-exist, then they will co-exist and
multiply. XDR schemas will probably stay around as well, personally I
quite like schematron, .....

David
Received on Monday, 22 May 2000 11:22:11 UTC

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