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From: "Klaus Backert" <KlausBackert@c...> > ;-) Is a namespace a set or not? Does it depend? Does it matter? An XML namespace is a collection of names (a vocabulary). A XML namespace has a URI. A URI identifies a WWW resource. A WWW resource may have one or more retrievable entities. No-one can agree what should be retrievable. But a URI is a useful thing. So RDDL provides one answer. An XML schema has symbols in a "symbol space". These "symbols" are names in XML namespaces but potentially qualified by their parent element. These are sometimes called "local elements" versus "global elements". For example, an element X could have a complex type definition in which contains local element declarations for an element X. So a name in a namespace does not always have a 1:1 association with a particular schema definition. Similarly, the elements in a whole namespace may be used in different ways by different schemas which use elements from the namespace. But often there will be one general or typical schema for a namespace. Yet variants can be expected over time due to maintanance, etc. So a namespace may be a set, but that does not mean an element in a particular namespace will always have the same content model etc. Cheers Rick Jelliffe
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