With each individual module having its requirements and low level class model definition, the system as a whole and the interactions between each module can now be designed.
The class diagrams of each module can be combined to form Figure 3.5. The different associations between classes show that there is a one to one relationship between all three modules, and that the two interface modules are required in order for the system to have minimal functionality. The NLP module can be removed and not stop the system from functioning (assuming it will have a limited capability mode where output from ViaVoice is sent directly to the animation interface).