RFC 2119 (Key Words for Use in RFCs)

RFC 2119 defines specific words like "MUST," "SHALL," "SHOULD," and "MAY" used in technical documents to indicate the level of obligation or recommendation. For example, "MUST" means something is mandatory, while "SHOULD" suggests a recommended best practice but not mandatory. These words help ensure clarity and consistency across technical standards and protocols, making it clear what actions are required, optional, or discouraged in implementation and compliance.