[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Namespaces, schemas, Simon's filters.
Tim Bray wrote: > > It's difficult for Matt Fuchs and I to have a straightforward > discussion because there's some terminology getting in the > way: Matt calls elements which are in a namespace "global" and > those which aren't "local". I suspect that he associates some > [schema-related?] semantics with the terms "local" and > "global". I don't believe Matt is saying this at all. Global and local refer to the scope of definitions, not identifiers. Furthermore, local element types can be in a namespace or not, depending on the elementFormDefault flag. The problem is actually at the level of definitions. The thinking that DTDs leads us to and that the namespaces spec reinforces is that an identifier uniquely identifies an element type and that this element type has a single definition. This doesn't play well with local element types, as has already been pointed out. The problem is that, if a local element type is in a namespace, it can have the same identifier as another local element type defined elsewhere. Most reasonable people would say that these are two different identifiers, but that the namespace spec, which is built on the concept of universal identifiers, doesn't support this. In other words, local element types effectively introduce a per-parent-element-type traditional namespace with which to discriminate the different local element types, just like local attributes effectively introduce a per-element-type traditional namespace with which to discriminate the different local attributes. Put yet another way, local element types don't play well (at all) with XML namespaces and contradict one of the fundamental assumptions of the namespaces specification -- that element types can/should have universally unique identifiers. -- Ron
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