Basic Use Case Diagram Symbols and NotationsSystemDraw your system’s boundaries using a rectangle that contains use cases. Place actors outside the system’s boundaries.Use CaseDraw use cases using ovals. Label the ovals with verbs that represent the system’s functions.ActorsActors are the users of a system. When one system is the actor of another system, label the actor system with the actor stereotype.RelationshipsIllustrate relationships between an actor and a use case with a simple line. For relationships among use cases, use arrows labeled either “uses” or “extends.” A “uses” relationship indicates that one use case is needed by another in order to perform a task. An “extends” relationship indicates alternative options under a certain use case.