Cart
[Home] [By Thread] [By Date] [Recent Entries]
In XML 1.0, the element's content model is its type. Instances of the type are found in instance documents. If one type contains another type, the containment relationship is visible in the instance document. XML Schema "types" are used within the schema to define element content models. They are twice removed from instance documents. They are, in effect, tree-structured parameter entities, with relations such as "extention-of" or "restriction-of" defined on them. These relations are completely invisible in instance documents. Any computer program that relies on those relations either must have access to the XML schema document or work with (as yet unspecified) PSVI, which has to be produced by the validating parser. There may well be useful programs that rely on Schema type relations, but it seems unreasonable to burden every validating parser with the task of understanding those relations and translating them into a "heavily-decorated DOM" data structure. So, it would be a good thing, IMO, if XML Schema were *re-factored* into the validating part (such as RELAX NG) and a "complex-type-relations" part, for use in specialized applications. Alexander Nakhimovsky http://cs.colgate.edu/faculty/sasha/adn.htm
|
