A use case diagram is a graphical view of some or all of the actors, use cases, and their interactions identified for a system. Each system typically has a Main Use Case diagram, which is a picture of the system boundary (actors) and the major functionality provided by the system (use cases). Other use case diagrams may be created as needed. Some examples follow:
A diagram showing all the use cases for a selected actor
A diagram showing all the use cases being implemented in an iteration
A diagram showing a use case and all its relationships
CREATING THE MAIN USE CASE DIAGRAM IN RATIONAL ROSE
Double-click on the Main diagram ...