Use case diagrams typically represent the context of a system and system requirements.
To design use case hierarchy:
- Usually, you begin at a high level and specify the main use cases of the system.
- Next, you determine the main system use cases at a more granular level. As an example, a "Conduct Business" use case can have another level of detail that includes use cases such as "Enter Customers" and "Enter Sales."
- Once you have achieved the desired level of granularity, it is useful to have a convenient method of expanding or contracting the use cases to grasp the scope and relationships of the system's use case views.