| |||
| 强制约束 (A constraint that requires every instance of an object type's population to play that role. With a disjunctive mandatory role constraint, each member of the object type's population must play at least one of the roles indicated) | |||
| |||
| 强制约束 (A constraint that requires every instance of an object type's population to play that role. With a disjunctive mandatory role constraint, each member of the object type's population must play at least one of the roles indicated) | |||
