GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc8174

Internet Engineering Task Force (IETF) B. Leiba Request for Comments: 8174 Huawei Technologies BCP: 14 May 2017 Updates: 2119 Category: Best Current Practice ISSN: 2070-1721

     Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words

Abstract

 RFC 2119 specifies common key words that may be used in protocol
 specifications.  This document aims to reduce the ambiguity by
 clarifying that only UPPERCASE usage of the key words have the
 defined special meanings.

Status of This Memo

 This memo documents an Internet Best Current Practice.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 BCPs is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc8174.

Leiba Best Current Practice [Page 1] RFC 8174 RFC 2119 Clarification May 2017

Copyright Notice

 Copyright (c) 2017 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
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  Clarifying Capitalization of Key Words  . . . . . . . . . . .   3
 3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
 4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
 5.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
 Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1. Introduction

 RFC 2119 specifies common key words, such as "MUST", "SHOULD", and
 "MAY", that may be used in protocol specifications.  It says that the
 key words "are often capitalized," which has caused confusion about
 how to interpret non-capitalized words such as "must" and "should".
 This document updates RFC 2119 by clarifying that only UPPERCASE
 usage of the key words have the defined special meanings.  This
 document is part of BCP 14.

Leiba Best Current Practice [Page 2] RFC 8174 RFC 2119 Clarification May 2017

2. Clarifying Capitalization of Key Words

 The following change is made to [RFC2119]:
 === OLD ===
 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:
 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.
 === NEW ===
 In many IETF documents, several words, when they are in all capitals
 as shown below, are used to signify the requirements in the
 specification.  These capitalized words can bring significant clarity
 and consistency to documents because their meanings are well defined.
 This document defines how those words are interpreted in IETF
 documents when the words are in all capitals.
 o  These words can be used as defined here, but using them is not
    required.  Specifically, normative text does not require the use
    of these key words.  They are used for clarity and consistency
    when that is what's wanted, but a lot of normative text does not
    use them and is still normative.
 o  The words have the meanings specified herein only when they are in
    all capitals.
 o  When these words are not capitalized, they have their normal
    English meanings and are not affected by this document.
 Authors who follow these guidelines should incorporate this phrase
 near the beginning of their document:
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
    NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
    "MAY", and "OPTIONAL" in this document are to be interpreted as
    described in BCP 14 [RFC2119] [RFC8174] when, and only when, they
    appear in all capitals, as shown here.
 === END ===

Leiba Best Current Practice [Page 3] RFC 8174 RFC 2119 Clarification May 2017

3. IANA Considerations

 This document does not require any IANA actions.

4. Security Considerations

 This document is purely procedural; there are no related security
 considerations.

5. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.

Author's Address

 Barry Leiba
 Huawei Technologies
 Phone: +1 646 827 0648
 Email: barryleiba@computer.org
 URI:   http://internetmessagingtechnology.org/

Leiba Best Current Practice [Page 4]

/data/webs/external/dokuwiki/data/pages/rfc/rfc8174.txt · Last modified: 2017/05/19 05:26 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki