[rfc-i] Drafting issue... use of MAY

Phillip Hallam-Baker phill at hallambaker.com
Tue May 1 17:16:30 PDT 2018


On Tue, May 1, 2018 at 1:03 PM, John Levine <johnl at taugh.com> wrote:

> In article <CAMm+LwgBFWW2GoemjDG3nVEO2=RLSH9XO3+uwRaQdi75oq=tyg at mail.
> gmail.com> you write:
> >Quite often in a spec, I find myself writing something like this:
> >
> >A Frame MAY be either buffered or unbuffered...
> >
> >Frames are either buffered or unbuffered...
>
> >Which is correct? I am thinking the second because it is not actually
> >normative, it is by definition which is not the same thing.
>
> I agree.  It is a good idea to reread RFC 2119 every once in a while
> to remember what the words mean.
>
> MUST doesn't mean "do this or die", it means "do this if you want to
> interoperate."  MAY means there are different ways to do something all
> of which will interoperate.
>
> I find relatively few uses for MAY, but one of them would be "letters
> in domain names MAY be in uppper or lower case."
>

​No. I thought that but actually it is wrong. You should have a MUST there.

Applications MUST accept letters in domain names in either ​upper or lower
case and treat these as equivalent.

This only occurred to me earlier today. A MAY for a generating party turns
into a MUST for the interpreter.
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