1. Authoritative statement of what to do or not to do in a specific situation, issued by an appropriate person or body. It clarifies, demarcates, or interprets a law or policy.
2. Statement that establishes a principle or standard, and serves as a norm for guiding or mandating action or conduct. Rules may be divided into four general categories: (1) Folklore: Unpublished rules that are conveyed by behavior and are implicitly understood. (2) Guidelines: Commonly published and recommended practices that allow some discretion with their interpretation and use. (3) Mandates: Published commands that may not be ignored in any circumstance and whose violation is punished. (4) Policies: Published rules that imply a predicted behavior and whose violation may be permitted or tolerated under certain circumstances.