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6.3.1.3.4. Standard fact types for compa... > 6.3.1.3.4. Standard fact types for c... - Pg. 170

6.3 Fact types 149 But what if the entity class requires multiple attributes to identify each instance? For example, motor vehicle registration numbers in Australia are only unique within the state of registration: that is, two different vehicles registered in different states may have the same registration number. Thus to uniquely identify a registered motor vehicle in Australia, it is necessary to specify the state as well as the registration number. Using only identification fact types, the best we could do would be F52. motor vehicle is identified using registration number/ registration number identifies motor vehicle F53. motor vehicle is identified using state name/ state name identifies motor vehicle However, neither of these fact types is appropriate, since neither registration number nor state name uniquely identifies a motor vehicle. If it is necessary to specify the reference scheme (means of identification) for each entity class or object class (and I believe it is), fact types like the following are required for each entity class or object class which has a multi-attribute reference scheme: F54. motor vehicle is identified using motor vehicle identifier/ motor vehicle identifier identifies motor vehicle