--On Wednesday, August 31, 2011 23:10 -0400 Sam Hartman <hartmans-ietf@xxxxxxx> wrote: >>>>>> "Eric" == Eric Burger <eburger@xxxxxxxxxxxxxxxxxx> writes: > > Eric> This highlights an interesting issue as an RFC goes > from PS to Eric> IS. I would offer that most SHOULDs in a > document will, if Eric> there are real implementations out > there, migrate to MUST or Eric> MUST NOT. > Eric> On Aug 31, 2011, at 9:57 AM, hector wrote: > > Hmm. Most of the times I use SHOULD I'd expect them to stay > SHOULD. SHOULD doesn't mean "this feature is desired," it > means "do this unless you have justification for doing > something else." There are a few cases (new algorithms) where > you mean SHOULD+ (we'll move to MUST in the future) but often > you mean do this unless you're in a constrained environment, > or you know you won't need it or something like that. In those > cases, SHOULDS tend to stay SHOULDS. +1 Exactly right. Indeed, if I agreed with Eric's view, I'd think we should abolish SHOULD and SHOULD NOT (almost) entirely, replacing them with temporary qualifications for MUST that would convey "not quite sure about this yet, but MUST is certainly our intention". "Tentative" or "Provisional", with appropriate IETF-specific definitions, would be two such words. Note that this loops back to the the discussion about conformance and certification. The standards bodies whose principal concerns about about conformance and certification cannot use what we call SHOULD because one cannot build a conformance test around a case that might have exceptions, especially exceptions that are not completely enumerated. They can, and do, use what we periodically describe with language like "MUST implement but are not required to configure in operation" (and, to add to the confusion, sometimes call that "SHOULD use"), but the conformance test then checks only for the implementation and, perhaps, for the presence of the knob. john _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf