The participants will learn how to express and manage functional requirements of large-scale software. They will learn how to express use-case models at different levels of abstraction. First, at a high level, how a user utilizes the combined functionality offered jointly by multiple IT systems of an enterprise. Second, at a lower level, how a single system is to be used by its surroundings. In addition, they will also learn how to establish traceability between the different models. This traceability is key when ensuring that the combined systems offer the desired functionality at the enterprise level. It is also instrumental when introducing changes and enhancements.