Business rules define the constraints or structure a system (or portion of the business) must follow. Rules governing a business unit might be policies guiding or limiting certain behaviors. ("Hourly employees must clock in before they start work.") Business rules governing a system define the way it behaves, or the way users can interact with it. ("Only system administrators may access the XYZ system log.") Business rules should leave no room for misunderstanding; they should be as specific and granular as possible—without any ambiguous wording or irrelevant information—and they should stand alone as clear, guiding statements, with no need to reference other requirements. Business rules provide the basis for process and systems requirements, and thus should be managed like any other requirement.