On 30/03/2016 05:34, John C Klensin wrote:
--On Tuesday, March 29, 2016 08:58 +1300 Brian E Carpenter
<brian(_dot_)e(_dot_)carpenter(_at_)gmail(_dot_)com> wrote:
...
The other words (must, shall, required, not) mean what they
always mean. The only argument for upper-casing them is
aesthetic symmetry. If a spec uses alternatives like
mandatory, necessary or forbidden, they are just as powerful.
...
Actually, when 2119 is referenced, Section 6 attaches particular
interoperability semantics to MUST, SHALL, etc., that are not
part of the plain-English meaning of those words. Section 6
seems to be ignored most of the time but cited when it supports
an axe someone wants to grind about use of conformance language.
My claim is that even section 6 does *not* change the meanings
of the categorical words in a spec. If it says that something
must or must not happen, either the statement is redundant or
it is essential for interoperability, whether it's written
in upper case Courier New or in runes.
But it doesn't matter. It's the SHOULDs and MAYs that require
precision in their use.
Brian