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From: Mike.Champion@S... > > 3. XHTML is more a doucment format than a data format, so the > > reasoning is slightly blurred > DTDs are too limited to be used effectively for "data", but never heard that > XSDs are not fully suitable for "documents". Lets take an example of XSL-FO. Inside the box, it is a tree in which a node can override certain properties of its ancestor--but if the ancestor does not have those properties, the node cannot. In XML Schemas, to simulate this would require an exploding number of declarations and type/element names. XML Schemas is no worse than DTDs for handling inheritence effects but not much better: indeed, if the inheritance effect comes from an ancestor and there can be lots of different properties effected, there is a combinatorial explosion than makes it impractical to model. (One would make a slack schema allowing everything, then use Schematron to detect co-occurrance constraints.) Is XSL-FO "data" or a "document"? I think the better distinction is between "inheritence-flat" documents (e.g. database data) and "inheritence-rich" documents (e.g. idiomatic markup languages and executable languages). Cheers Rick Jelliffe
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