[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: DTDs, W3C Schemas, RELAX NG, Schematron?
Eddie Robertsson scripsit: > See comments below. Thanks for the review. > > 5) RNG allows a (simple) datatype to be restricted not only by facet, > > but by explicit extension and exception. One can write 'xsd:integer - > > "0"' to mean a nonzero integer (although unfortunately "00" will still > > validate), or 'xsd:integer | "Inf" | "+Inf" | "-Inf"' when a value may > > be integral or infinite. > > This can quite easily be done using union types in XML Schema I see that. -1 for me. > or if you want to > restrict an integer type you can use the various facets provided for this. But restrictions by facet are only pre-set ones. You can restrict an integer to be between -5 and +5, but you can't restrict a token, say, not to be "foo". Whereas in RNG that is just xsd:token - "foo". > > 11) RNG lists consist of non-whitespace separated by whitespace, and the > > non-whitespace need not be all of the same (simple) type. A pattern like > > "list {xsd:integer, xsd:string}+" is perfectly valid, and matches content > > like "2 foo 5 bar". > > This can be done by creating a list type from a union type in XML Schema. True. I didn't word this sharply enough. If you want a list consisting of alternating numbers and strings, RNG can do that but XSD can't: a list type created from a union type is "list {(xsd:integer|xsd:string}+}", and matches things like "2 5 foo bar". > > What does RNG lack? Mainly, it has no notion of keys or other identity > > constraints, except for DTD-compatible ID and IDREF(S). RNG validators > > also don't provide any sort of PSVI, and indeed only a subset of legal > > RNG schemas would be able to produce type tags at all (validity is always > > decidable, but just *which* rule(s) were applicable may not always be). > > What about default values? Right. I was lumping that with the PSVI under the heading of infoset augmentations. I will mention it explicitly in the next version. -- John Cowan <jcowan@r...> http://www.reutershealth.com I amar prestar aen, han mathon ne nen, http://www.ccil.org/~cowan han mathon ne chae, a han noston ne 'wilith. --Galadriel, _LOTR:FOTR_
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