Classifier Role :- It classifies a role. Association Role :- It shows the relation between two Classifier roles.Multi-Object :- It used to show operation related to entire set of objects rather than on a single object. Constraint :- Conditions which must be maintained as true in order that system is valid.
2-Element Constraint: - It shows a constraint on two classes or associations. OR
constraint: - It shows an OR constraint on two classes or associations.