Have you ever wondered how the business rules are stored in CRM ? Have you ever thought 'Business Rules' are also one of the Workflow category? Even though they may not look like, but they are one among them. Yes, 'Business Rules' is also a type of Workflow.
Below is the screenshot of the Workflow category in CRM 2013. As like others Business Rules (PBL) details are also in Workflow Tables with Category = 2