Lifeline :- This say’s that there exist some condition on the object lifetime.
Message: - It shows communication between objects that conveys information and results in an action.
Message (call):- Its same like message but also conveys some information and results in action.All messages have same definition as the Message (Call) given above.
2-Element Constraint: - It shows a constraint on two classes or associations.
OR constraint: - It shows an OR constraint on two classes or associations.