Hi,
o When these words are not capitalized, they have their normal
English meanings; this document has nothing to do with them.
There are, and probably always will be, standards track documents
that do not cite RFC 2119 and do not use upper-case normative
keywords. In those documents, we will find usage of 'should' and
'should not' whose interpretation will remain ambiguous. (Does
'should' mean 'must unless there is a very good reason' or something
less?) I think that ambiguity is worth pointing out. I don't think
'must' and 'may' are ambiguous in that way.
However, that point leads me to another issue:
Authors who follow these guidelines should incorporate this phrase
near the beginning of their document:
I think that 'should' needs to be 'must'. Otherwise we could in theory
have documents using both 'MUST' and 'must' with no disambiguation.
(This is also a bug in RFC 2119.)
To reduce the number of reserved key words, the following key words
are deprecated, and no longer have special meanings defined by BCP
14:
REQUIRED, SHALL, SHALL NOT, RECOMMENDED, NOT RECOMMENDED, OPTIONAL
I will be glad to see the back of SHALL, but I object to deprecating
the adjectives. They are useful - indeed, sometimes required - for
the construction of readable sentences and, for example, tables of
RECOMMENDED and OPTIONAL values.
Regards
Brian Carpenter
On 10/08/2016 07:55, internet-drafts(_at_)ietf(_dot_)org wrote:
A New Internet-Draft is available from the on-line Internet-Drafts
directories.
Title : Ambiguity of Uppercase vs Lowercase in RFC 2119 Key
Words
Author : Barry Leiba
Filename : draft-leiba-rfc2119-update-00.txt
Pages : 4
Date : 2016-08-09
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, and by deprecating some versions of the key
words.
The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-leiba-rfc2119-update/
There's also a htmlized version available at:
https://tools.ietf.org/html/draft-leiba-rfc2119-update-00
Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.
Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/
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