Key words for use in RFCs to Indicate Requirement Levels

This RFC 2119 was published in 1997.


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:

RFC 2119 introduction

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