The Implementation Classes tab in the use case property sheet shows the list of classes, or interfaces used to implement a use case. A use case is generally a task or service, represented as a verb. When analyzing what a use case must do, you can identify the classes and interfaces that need to be created to fulfill the task, and attach them to a use case.
To add a class or interface to the list, use one of the following tools:
For example, a use case ship product by express mail needs the classes Shipping, Product, and Billing to perform its task:
You can display the names of the use cases associated with a class on the Dependencies tab of its property sheet.