AbstractKey topics in this chapter4.1 Introduction to high-level requirements4.2 System actors4.3 System use cases4.4 How to find system use cases in the business use case model?4.5 How to find system use cases in BPMN diagrams?4.6 How to find system use cases in machine state diagrams?4.7 Requirements4.8 Preliminary conceptual model4.9 DiscussionQuestions