Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words

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Network Working Group                                           B. Leiba
Internet-Draft                                       Huawei Technologies
Updates: 2119 (if approved)                              August 09, 2016
Intended status: Best Current Practice
Expires: February 08, 2017

       Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words


   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, and by deprecating some versions of the key

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1.  Introduction

Leiba                  Expires February 08, 2017                [Page 1]
Internet-Draft           RFC 2119 Clarification              August 2016

   RFC 2119 specifies common key words, such as "MUST", "SHOULD", and
   "MAY", that may be used in protocol specifications.  It says that
   those key words "are often capitalized," and that 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.  It also
   reduces wording conflicts by deprecating some synonymous key words.
   This document will become part of BCP 14 when it is approved.  [[RFC-
   Editor: Please change the previous sentence to "This document is part
   of BCP 14."]]

1.1.  Some Notes for Reviewers (not for publication)

   [[RFC-Editor: Please remove this section before publishing.]]

   This update is intentionally small and focused, and quite
   intentionally updates, but does not replace, RFC 2119.  The author
   considers it important to retain the reference to RFC 2119 because of
   the general familiarity with the number, and to phase in the use of
   "BCP 14".  Note, though, that the References section uses the RFC
   numbers, not the BCP number.  This is because is needs to be clear
   when a document has adopted this update, and the dual reference to
   RFC 2119 *and* this document gives that clarity.

   The point has been made by some that having case be significant to
   the meanings of words is unusual and may be a bad idea.  There is
   specific concern about causing confusion to readers whose native
   languages do not have a distinction between upper and lower case
   (consider Chinese and Hebrew, for example).  The author believes this
   has been discussed and addressed, and that those maintaining this
   point are in the rough.  That said, it may still be worth continuing
   the discussion a bit.

   There have been suggestions that while we're here we should consider
   a broader BCP 14 update that also talks about proper use of the key
   words, when they should not be used, avoiding overuse, and so on.
   The author agrees, but thinks is best to keep that as a separate
   effort, as coming to consensus on such an update is likely to be much
   more difficult, and is likely to take much longer.

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
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