On 8/31/11 12:36 AM, Eric Burger wrote:
My interpretation of what you wrote is that in your mind there is absolutely no
difference between a SHOULD and a MAY. They are both optional, and you
implement whatever you have time to implement, with SHOULD's prioritized higher
than MAY's.
Even if that is not what you mean, it is what many implementors do.
Peter's document makes a change to 2119 that nobody has mentioned yet,
and I think it is the one that is causing most of the strife in this
discussion.
Hector is exactly right. SHOULDs are optional. MAYs are optional. What
he fails to point out is that MUSTs are also optional. They're all
optional because.....
RFC 2119 does *not* provide *conformance* terms.
Peter's document uses the words "conform" and "conformance". They appear
nowhere in RFC 2119. RFC 2119 was not coming up with a vocabulary for
things that MUST be done if one is to conform to a specification. It
came up with terms for things that MUST be done to interoperate. Or
SHOULD be done (with a pretty specific meaning of "SHOULD"). Or MAY be done.
If you think that the presence of SHOULD means that you don't have to
implement a particular thing in a document, you're wrong. SHOULD means
that "may exist valid reasons in particular circumstances to ignore a
particular item, but the full implications must be understood and
carefully weighed before choosing a different course." That is, if you
don't do what is in the statement marked by "SHOULD", there is a good
chance you will fail to do something that is "required for
interoperation" or to engage in "behavior which has potential for
causing harm" unless you understand the implications.
But if you think that the presence of SHOULD (or MUST) means that you
*have to* implement a particular thing in a document, you're also wrong.
There are not protocol police. We don't do conformance checks in the IETF.
You might have a contract with someone who requires you to implement all
MUSTs (or SHOULDs unless you provide an explanation of why you didn't).
That's up to them. But the IETF ought not be in the business of
conformance requirements.
Maybe we do write documents now with conformance requirements. Maybe
this ship has sailed. Maybe the elephant is on board. I hope not.
Clarifying "SHOULD" is a fine thing. Making it conformance language is
not. I don't like the 2119bis document in its current form.
pr
--
Pete Resnick<http://www.qualcomm.com/~presnick/>
Qualcomm Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102
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