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Chris Lilley wrote: > > Unfortunately I came across EBNF long before I came accross DTD syntax, > so about half an hour after meeting DTDs I was, like, what do you mean > it can't express that this attribute is a url? Why can't it express that > this attribute is an ISO standard date? I can guarantee you today that the XML schema effort will not allow you to express everything that EBNF will so if that's your standard it will fail. But even if we use EBNF as our standard: do you know of any programming languages expressed entirely in EBNF? Or even entirely in *any formalism*? > Yes, validation is important - and I mean real validation, with no > critical-path human-readable comments in the DTD and multiple utilities > to check different aspects of validity (like separate scripts to ensure > that an attribute is a valid date or customer number). It will never be the case that it will be possible to write schemas that are so tight that they remove the need for comments that describe additional constraints to other human beings. There will always be a need not only for multiple schema languages but also for the ultimately flexible schema language: prose text. Luckily, eliminating all other schema languages is not a goal of the W3C schema language effort. > So what is critically needed is a real, namespace-aware, schema > language that can be used to do real validation. I hear a lot of users saying that. They don't seem to realize that there is no such thing as "real validation" there is only "the validation I need to do today." Ten years from now, we'll be griping that XMLSchemas don't do "real validation" for some other arbitrarily advanced definition of "real." -- Paul Prescod - ISOGEN Consulting Engineer speaking for only himself http://itrc.uwaterloo.ca/~papresco "A year ago, when Ernest Pecounis said he wanted to bring Linux into the state agency he works for, there was a swell of laughter from his colleagues. Guess who's laughing now." - http://www.zdnet.com/pcweek/stories/news/0,4153,393443,00.html 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/ and on CD-ROM/ISBN 981-02-3594-1 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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