Re: 2119bis

"George Willingmyre" <gtw@xxxxxxxxxxxxxxxxx> · Thu, 1 Sep 2011 10:00:18 -0400

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@xxxxxxxx 
  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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