Business specifications are essential to describe and understand businesses (and, in particular, business rules) independently of any computing systems used for their possible automation. They have to express this understanding in a clear, precise, and explicit way, in order to act as a common ground between business domain experts and software developers. They also provide the basis for reuse of concepts and constructs ("patterns") common to all - from finance to telecommunications -, or a large number of, businesses, and in doing so save intellectual effort, time and money. Moreover, these patterns substantially ease the elicitation and validation of business specifications during walkthroughs with business customers, and support separation of concerns using viewpoints.