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The UML class diagram below uses dashed hollow-triangle arrows for trait realization and ordinary arrows for stored references or navigable associations. Visibility is + for public and - for private.

GymEquipment implements Equipment. Performance and Prediction implement Functionality, each retaining one GymEquipment reference and registering itself with that equipment. Each equipment keeps a list of zero or more Functionality references; one functionality can in principle be registered with multiple equipment objects through the public method, although the supplied constructors register it only with their own equipment. Hence the generic registration association does not imply exclusive ownership or composition in UML.

There are two traits, one concrete equipment software class, and two concrete observer software classes. GymEquipment implements name, age, and weight as read-only values and overrides updateUserMeasures; the mutable measurement state and observer list are defined privately in Equipment. The diagram reflects the source, including deleteFunctionality returning a new list rather than mutating the stored list.