<reference anchor='RFC2119'>

<front>

<title abbrev='RFC Key Words'>Key words for use in RFCs to Indicate Requirement Levels</title>

<author initials='S.' surname='Bradner' fullname='Scott Bradner'>

<organization>Harvard University</organization>

<address>

<postal>

<street>1350 Mass. Ave.</street>

<street>Cambridge</street>

<street>MA 02138</street></postal>

<phone>- +1 617 495 3864</phone>

<email>sob@harvard.edu</email></address></author>

<date year='1997' month='March' />

<area>General</area>

<keyword>keyword</keyword>

<abstract>

<t>

   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:

<list>

<t>

      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.

</t></list></t>

<t>

   Note that the force of these words is modified by the requirement

   level of the document in which they are used.

</t></abstract></front>

<seriesInfo name='BCP' value='14' />

<seriesInfo name='RFC' value='2119' />

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</reference>