CHAPTER Business Rule Models 6 Business rules are the fourth and last business modeling discipline described in this book. Business rules shape the behavior of a business and guide the behavior of the business's employees. Business rules explain what is allowed and what is not allowed. A business rule model also explains the conse- quences of violation: what happens when a rule is violated. This chapter describes business rule models. Sometimes customers at a Mykonos restaurant leave before they finish their din- ner. Perhaps there is an emergency at home, and they must leave to tend to the