One document matched: draft-saintandre-2119bis-00.txt

Network Working Group                                     P. Saint-Andre
Internet-Draft                                       Cisco Systems, Inc.
Obsoletes: 2119 (if approved)                            August 29, 2011
Intended status: BCP
Expires: March 1, 2012


            Conformance Terms to Indicate Requirement Levels
                      draft-saintandre-2119bis-00

Abstract

   In many protocol specifications and related documents, special
   conformance terms (e.g., the uppercase words "MUST", "SHOULD", and
   "MAY") are often used to signify requirement levels.  This document
   defines these conformance terms and describes how they are to be
   interpreted in documents produced within the Internet Standards
   Process.  If approved, this document obsoletes RFC 2119 and changes
   its status to Historic.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 1, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.1.  MUST  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.2.  MUST NOT  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.3.  SHOULD  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.4.  SHOULD NOT  . . . . . . . . . . . . . . . . . . . . . . . . 4
     2.5.  MAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Boilerplate . . . . . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  Informative References  . . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 6






























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1.  Introduction

   In many protocol specifications and related documents, special
   conformance terms (e.g., the uppercase words "MUST", "SHOULD", and
   "MAY") are often used to signify requirement levels.  This document
   defines these conformance terms and describes how they are to be
   interpreted in documents produced within the Internet Standards
   Process [BCP9].  If approved, this document obsoletes RFC 2119 and
   changes its status to Historic.

   The discussion venue for this document is the <ietf@ietf.org> mailing
   list, for which archives and subscription information are available
   at <https://www.ietf.org/mailman/listinfo/ietf>.

   [[ NOTE TO RFC EDITOR: Upon publication, please remove the foregoing
   sentence. ]]


2.  Definitions

2.1.  MUST

   This term means that the feature or behavior is an absolute
   requirement of the specification, so that an implementation has an
   unconditional obligation to implement the feature or to behave as
   defined.  The terms "SHALL" and "REQUIRED" are equivalent to "MUST".

2.2.  MUST NOT

   This term means that the feature or behavior is an absolute
   prohibition of the specification, so that an implementation has an
   unconditional obligation to not implement the feature or to not
   behave as defined.  The term "SHALL NOT" is equivalent to "MUST NOT".

2.3.  SHOULD

   This term means that the feature or behavior is a limited requirement
   of the specification, so that an implementation has a conditional
   obligation to implement the feature or to behave as defined, unless
   there is a strong, explicitly described reason not to do so in
   particular circumstances.  Those who implement the specification or
   deploy conformant technologies need to understand and carefully weigh
   the full implications of violating the requirement before doing so.
   The term "RECOMMENDED" is equivalent to "SHOULD".







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2.4.  SHOULD NOT

   This term means that the feature or behavior is a limited prohibition
   of the specification, so that an implementation has a conditional
   obligation to not implement the feature or to not behave as defined,
   unless there is a strong, explicitly described reason to do so in
   particular circumstances.  Those who implement the specification or
   deploy conformant technologies need to understand and carefully weigh
   the full implications of violating the prohibition before doing so.
   The term "NOT RECOMMENDED" is equivalent to "SHOULD NOT".

2.5.  MAY

   This term means that the feature or behavior is truly a matter of
   preference.  One implementation can choose to implement the feature
   or behavior whereas another implementation can choose not to, without
   any resulting harm to interoperability.  An implementation that does
   not implement the feature or behavior needs to interoperate with
   another implementation that does do so, although perhaps with reduced
   functionality.  Likewise, an implementation that implements the
   feature or behavior needs to interoperate with another implementation
   that does not do so (except, of course, with respect to the defined
   feature or behavior).  The term "OPTIONAL" is equivalent to "MAY".


3.  Usage

   The conformance terms defined in this document ought to be used
   judiciously.  In particular, the absolute and limited requirements
   and prohibitions ought be used only to specify features and behaviors
   that are necessary for interoperability, or to forbid features and
   behaviors that have the potential to cause significant harm.  For
   example, such terms are not to be used to impose a particular method
   on implementers if the method is not necessary for interoperability.

   When it is not appropriate to use the conformance terms, authors can
   use a variety of alternative words and phrases, such as: "need to",
   "has to", or "mandatory" instead of "MUST"; "ought to", "strongly
   encouraged to", or "suggested" instead of "SHOULD"; and "might",
   "can", or "discretionary" instead of "MAY".  To prevent confusion,
   authors are strongly encouraged to use these alternative words and
   phrases instead of the lowercase versions of the conformance terms
   whenever possible, and to use the conformance terms only in their
   uppercase versions.







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4.  Boilerplate

   In order for the requirements force of the conformance terms to
   apply, authors who follow the guidelines specified herein need to
   incorporate this sentence near the beginning of their documents:

      The following conformance terms are to be interpreted as described
      in RFC XXXX: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT";
      "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY",
      "OPTIONAL".

   [[ NOTE TO RFC EDITOR: Upon publication, please change "XXXX" to the
   number assigned to this document. ]]


5.  Security Considerations

   The conformance terms defined in this document are frequently used to
   specify features and behaviors that have security implications.  The
   effects on security of not implementing a "MUST" or a "SHOULD", or of
   doing something the specification says "MUST NOT" or "SHOULD NOT" be
   done, can be very subtle.  Authors are strongly encouraged to
   elaborate the security implications of not conforming to requirements
   and recommendations, since many implementers do not have the benefit
   of the experience and discussion that produced the specification.


6.  IANA Considerations

   This document requests no actions of the IANA.


7.  Acknowledgements

   This document borrows text from [RFC2119]; Scott Bradner, the author
   of that document, is gratefully acknowledged.


8.  Informative References

   [BCP9]     Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.






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Author's Address

   Peter Saint-Andre
   Cisco Systems, Inc.
   1899 Wyknoop Street, Suite 600
   Denver, CO  80202
   USA

   Phone: +1-303-308-3282
   Email: psaintan@cisco.com









































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