The application build on the base of Navigator consists of three main groups of classes: Commands, Models and Views. Command serves the user’s instruction “what to do”, Model changes the state of the system and View presents the state of the system to user. Following the well-known “divide and rule” maxim, you can join the commands, models and views together in modules, also. Navigator widely uses Inversion of Control pattern (“you don’t need to call us, we call you ourselves”) that affects the applications’ architecture.