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James Robertson wrote: > > At 07:26 31/08/1998, John Cowan wrote: > | Learn to relax and live without DTDs. The new namespace proposal > | makes them useless anyway, so people are now trying to develop > | various replacements for them. > > Doesn't this statement make people scared?!? No, because it simply isnt so. Having namespaces merely expands the richness of the vocabulary available to document system designers. Applications for which XML DTDs are best suited will continue to use DTDs. Applications which can stand 100s of Ks of schema data will use instance syntax. Applications for which existing AFDR syntax (attributes for architectural forms) are clearly appropriate will use AFDR syntax. People who find that PIs fit will use them; people who like embedding markup in comments or creating their own embedded markup landuages will find some excuse to do that. The important thing is that document system designers understand when it is appropriate to use each one. Namespaces as now proposed do not make DTDs useless: as far as I can see the proposal does not really impact on whether a full DTD is useful or not much at all (except for the limited case of fixed or defualting attributes for the prefix and namespace name themselves, which has hardly been the prime use of DTDs up to now). The fact that DCD takes the namespace URI and uses it to key which DTD or schema to use is no different from what people do with attributes all the time: they use attribute values to figure out what processing is required for an element. XML wasnt designed on a minimalist principle (what is the smallest we can get away with?) but more on the optimalist principle (can we satisfy 80% of needs with something only 20% of the complexity?). As far as I can see, the XML WG has placed quite a high emphasis on keeping (SGML's) richness; the provision of Namespaces only confirms this impression (that richness is more important to the WG than terseness or minimalism). DTDs have proved themselves in the field for many years and dont require more defense; if other syntaxes arrive which are more appropriate in their own circumstances than DTDs, that is no slur on DTDs. Namespaces certainly provide a good set of hooks for external schemas, but such hooks can be provided in fixed attributes in DTDs just as readily as in attribute values in the instance. In fact, for size reasons, having namespace attributes declared in fixed attributes in DTDs may be more preferable than bloating the instance with repeated attributes. Counter to John Cowan, namespaces may, for some document types, make an explicit DTD *more* attractive, not less! Rick Jelliffe xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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