This specifies how many of a particular part should be in an instantiated composite type. For example, when a type of car is instantiated, it should have four wheels. Any relations to part specification will be replicated for each of the parts filling that specification in the instantiated composite. For example, if we have a object part specification for the front wheels, with part cardinality of two, then any connections, like one from the engine, will be instantiated for both wheels.