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RE: SHOULD vs MUST

"Eric Gray" <eric.gray@ericsson.com> Fri, 27 June 2008 19:32 UTC

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Subject: RE: SHOULD vs MUST
Date: Fri, 27 Jun 2008 10:55:38 -0500
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From: Eric Gray <eric.gray@ericsson.com>
To: dcrocker@bbiw.net, IETF Discussion <ietf@ietf.org>
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Dave,

> Scott Brim wrote:
> > My rule of thumb is: when you're writing the draft if something is
not a 
> > MUST, ask yourself "why not?" and write down your answer.  You can
be 
> > brief but make it clear that the SHOULD is a MUST with exceptions.
> 
> 
> This gets to an essential issue with IETF specification writing, as
well as 
> suggesting some of the distinction between MUST and SHOULD.
> 
> (By the way, I hope folks are clear that IETF use of these words as
normative 
> does not depend upon the case that is used?)

This is NOT true.  These terms are explicitly defined in all
capital letters to make it possible to distinguish when they
are being used as normative and when they are not.

One of the things RFC authors need to be careful about is to
ensure that they do capitalize these terms consistently.

In text that is not meant to be normative, the special terms
should be avoided - even in lower case - but this can lead to
exceptionally stilted use of the English language.

--
Eric
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