Much of the code in a legacy application, by some estimates as much as 80%, is devoted to tasks with only a marginal relationship to the business logic of the application. Business rule extraction lets you separate the application's business logic from data transfer and other tasks.
That makes the application easier to understand, document, maintain, and modernize. It also makes it easier to determine the overlap between legacy applications on the one hand, and any gaps in their functionality on the other.
Business Rule Manager (BRM) lets you batch edit rule attributes; create custom attributes suited to your particular needs; match input/output data elements with the business names you've assigned to them in your project glossary; and much more.