An abstract class that is the base for controller memberships for the table.
The association between a feature class and a topology has extra attributes&emdashfor example, the rank of the feature class. The association of a feature class and a geometric network also has extra attributes—for example, the enabled field. These are attributes of the feature class's membership in a controlling entity, be it the topology or the geometric network. They are attributes of the membership because they wouldn't exist if the feature class were not a member of the controller.
Each membership contains the data about the relationship between the feature class and the controlling entity (rank or enabled field, for example).