IF-Then statements that explain business policies and guideline and that are understandable to managers. James Taylor explains that "Business rules syntax allows for a great deal of flexibility that you cannot replicate in traditional programming languages. Rules may be written with English phrases such as 'If customer's age exceeds 65, then set customer's discount to .05'. "

According to Wikipedia, "Business rules or business rulesets describe the operations, definitions and constraints that apply to an organization in achieving its goals. For example a business rule might state that no credit check is to be performed on return customers. Others could define a tenant in terms of solvency or list preferred suppliers and supply schedules. These rules are then used to help the organization to better achieve goals, communicate among principals and agents, communicate between the organization and interested third parties, demonstrate fulfillment of legal obligations, operate more efficiently, automate operations, perform analysis on current practices, etc."

According to Scott Ambler "A business rule defines or constrains one aspect of your business that is intended to assert business structure or influence the behavior of your business. Business rules often focus on access control issues, for example, professors are allowed to input and modify the marks of the students taking the seminars they instruct, but not the marks of students in other seminars. Business rules may also pertain to business calculations, for example, how to convert a percentage mark (for example, 91 percent) that a student receives in a seminar into a letter grade (for example, A-). Some business rules focus on the policies of your organization, perhaps the university policy is to expel for one year anyone who fails more than two courses in the same semester."

Ronald Ross (2003) describes several basic principles of what he calls “the business rule approach”. He believes that rules should:

1. Be written and made explicit.
2. Be expressed in plain language.
3. Exist independent of procedures and workflows (e.g. multiple models).
4. Build on facts, and facts should build on concepts as represented by terms (e.g. glossaries).
5. Guide or influence behavior in desired ways.
6. Be motivated by identifiable and important business factors.
7. Be accessible to authorized parties (e.g. collective ownership).
8. Be single sourced.
9. Be specified directly by those people who have relevant knowledge (e.g. active stakeholder participation).
10. Be managed.

from

Power, D., "James Taylor Interview: Automating Decision Making", DSSResources.COM, 10/6/2006.

http://en.wikipedia.org/wiki/Business_rules

http://www.agilemodeling.com/artifacts/businessRule.htm