Key words for use in RFCs to Indicate Requirement Levels
RFC 2119, “Key words for use in RFCs to Indicate Requirement Levels”, is a Best Current Practice document published in March 1997 by S. Bradner. It has since been updated by RFC 8174. The canonical text is published by the RFC Editor.
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. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
What “Best Current Practice” means
Documents the IETF community's recommended operational or procedural practice rather than a protocol specification.
The canonical text of RFC 2119 is hosted at rfc-editor.org. Available in TXT,HTML.
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