Key Words of Conditional Language of Requirements Levels
In many standards track documents conditional words are used to signify the requirements in the specification. These words are prefered to be capitalized. This document defines these conditional 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 additional key words to words described in RFC2119 are; "IF, THEN", "ELSE IF", "ELSE".