You have identified the use cases for the system or application
and captured them in a use case model. The next step in the development
process is to build on the use case model by describing the structure
of the system. In this phase, you analyze the application domain to
discover the domain requirements of the system and create a high-level
object model that describes how the system will be logically constructed.
You can use class diagrams and sequence diagrams to capture the logical
implementation of the functional requirements that you described in
the use case model.