While we are on the topic of definitions I hoped to stimulate thinking and we
can reach the conclusion that best meets our needs.
The source parent document is at the URL on the ANSI web site
http://publicaa.ansi.org/sites/apdl/Documents/Standards%20Activities/International%20Standardization/ISO/ISO_IEC_Directives_Part2.pdf
ISO/IEC Directives, Part 2 Rules for the structure and drafting of
International Standards
George T. Willingmyre, P.E.
President, GTW Associates
Spencerville, MD USA 20868
301.421.4138
www.gtwassociates.com
----- Original Message -----
From: Mykyta Yevstifeyev
To: ietf(_at_)ietf(_dot_)org
Sent: Thursday, September 01, 2011 9:48 AM
Subject: Re: 2119bis
George,
We currently use MUST in regular cases and SHALL when we either want not to
create confusion where non-normative "must" is used or for aesthetic reasons,
eg. to make a requirement look not so strict as MUST implies (even though
formally they both have similar force). I personally use SHALL when I mean "it
is to be so" and not strict "it is mandatory and obligatory and compulsory and
<...> to be so".
CAN and CANNOT are an interesting idea, but they have little in common with
conformance. Current 2119 language, as primarily used in
<http://tools.ietf.org/html/rfc1123#page-11>, was intended to clear up the
requirements on support of particular feature(s). Yes, it is sometimes desired
to express possibility and allowance, but IMO simple "can" and "cannot" are
fine for this purpose.
I don't actually think Annex H of <I don't know what since you're providing
only part of it> should be referenced in 2119bis.
Mykyta Yevstifeyev
01.09.2011 16:17, George Willingmyre wrote:
I offer for consideration in the attachment the ISO and IEC requirements
for use of the
terms "Shall" ; Shall not"; "Should"; "Should not" ; "May"; "Need not" ;
"Can'; "Cannot" in ISO and IEC standards.
This document explains why ISO/IEC selects "Shall" and "Shall not" rather
than "Must" and "Must not" to denote mandatory requirements.
"Do not use "must" as an alternative for "shall". (This will avoid any
confusion between the requirements of a document and external statutory
obligations.)"
It is in the interests of IETF to contemplate and perhaps reference this
ISO/IEC document somehow in our definition of the terms below
2.1. MUST . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. MUST NOT . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. SHOULD . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.4. SHOULD NOT . . . . . . . . . . . . . . . . . . . . . . . . 4
2.5. MAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
George T. Willingmyre, P.E.
President, GTW Associates
Spencerville, MD USA 20868
301.421.4138
www.gtwassociates.com
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