Updated by: 8174 BEST CURRENT PRACTICE

Errata Exist

Network Working Group S. Bradner Request for Comments: 2119 Harvard University BCP: 14 March 1997 Category: Best Current Practice Key words for use in RFCs to Indicate Requirement Levels Status of this Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. Abstract In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. Authors who follow these guidelines should incorporate this phrase near the beginning of their document: The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119. Note that the force of these words is modified by the requirement level of the document in which they are used. 1 . MUST 2 . MUST NOT 3 . SHOULD 4 . SHOULD NOT Bradner Best Current Practice [Page 1]

RFC 2119 RFC Key Words March 1997 5 . MAY 6 . Guidance in the use of these Imperatives 7 . Security Considerations 8 . Acknowledgments Bradner Best Current Practice [Page 2]