in the relationship that involves the entities PART_DETAIL, a type of part contains many items and there is an unspecified upper bound. thus, the minimum-maximum cardinality is (1, N) for the entity PART_DETAIL.on the other hand, an item of a computer part must belong to one, and only one, part type. the minimum-maximum cardinality is (1, 1) for the entity PART. the existence of the PARt_DETAIL entity instance depends on the existence of the PART. therefore, the part ID is required.