Business rules are rules that govern the way a business operates. For purpose of legacy business rule extraction, we narrowed the OMG definitions to the following. A business rule is a combination of conditional and imperative logic that changes the state of an object or data element. An example might help clarify this definition. Business rule extraction identifies and captures any combination of conditional and imperative statements and isolates these statements to facilitate the understanding and reuse of knowledge contained within legacy information systems.
Rules can invoke other rules and be represented within a rule hierarchy.
Business rule extraction documents which business functions are being performed by a given set of programs and systems. Consolidating and reusing captured business rules extends this process by making these rules available to design and development teams. Rule extraction and reuse are a means to an end, and that end depends on the tactical and strategic requirements of a given enterprise. Big picture requirements drive the need to perform business rule extraction and reuse. Executives should only sanction rule extraction when there is a valid business reason.