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Nice to hear from you Rick. Glad to hear you are not "overdone" at present (in Wulai). Some of us "hard-boiled" old eggs take longer to get up steam! > Why should XML Schemas have > key constraints and uniqueness, but not multiple inheritance? With the relational database bias of RDF showing itself at W3C do you really need to ask this question :-) Interestingly the abstract element concept shows the influence of the UML modellers. It maps nicely to UML stereotypes, but as this is a feature of UML that is little understood it will take a while for people to wake up to what is happening here. (AFs for classes!) >Until we have > a broad range of different experimental and commercial languages for > constraining certain things in relation to other things, we cannot know > what is powerful and convenient. Agreed. The real problem is expressing constraints that apply across classes, rather than inheritable property constraints. (If class X > 12 do not require class Y, but do check that class Z is restricted to values A or B.) This is one of the big "holes" in ebXML. We know its boundaries, but are having difficulty filling it in. Martin
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