Each partitioning that is not a life-cycle partitioning must be associated with a classifying attribute that belongs to the entity type that it partitions.
Each subtype must be identifiable by a classifying value, or a range of classifying values.
A fully enumerated partitioning must divide the entity type it partitions into two or more subtypes.
Each entity type can have only one life-cycle partitioning and that partitioning must be fully enumerated.
A subtype within a non life-cycle partitioning must have at least one special attribute or relationship membership.
