The following people will use the implementation subsystem:

• Software architects use it to structure the implementation model into parts that can be separately integrated and tested.
• Those who design the next version of the system use it to understand the structure of the implementation model.
• Implementers of other parts of the system use it to understand how their functionality can be used.
• Those who test the subsystem use it to plan testing activities.
• The project manager uses it as a basis for allocating the implementation work.

The implementation subsystem is the physical analogue of the design package. The implementation model and the implementation subsystems are initially defined in the implementation view, and so are of primary importance at development time.