Abstract
This chapter presents the sub-models of the 4EM language as well as the basic principles of using them. The sub-models are the Goals Model, the Business Rules Model, the Concepts Model, the Business Process Model, the Actors and Resources Model, the Technical Components and Requirements Model, as well as the use of inter-model links that connect the sub-models. All sub-models will be presented with their components (notation), a guide for developing them (driving questions) and an example. As a running example we will use A4Y case described in Chap. 6.