Extending the behavior of use cases
In UML modeling, when you
draw use-case diagrams, you communicate the essence of the system
or application without exposing unnecessary details. It's generally
good practice to hide the complexity of the system, but there are
times when you might need to expose details. You can depict these
details in their own use cases and connect them to base use cases,
which enables you to reveal information that would otherwise be hidden.