I think I'm essentially agreeing with Eric Rescorla here, but perhaps
phrasing it differently may help.
On Sat Jun 21 14:31:03 2008, Lawrence Conroy wrote:
I had read 2119 to mean that a MUST was unconditional
- do this or be non-complaint.
That's a reasonable assessment, given RFC 2119.
Do you believe that MUST can have an "unless" clause?
I think that any MUST X unless Y can essentially be rephrased as one
of "MUST (X or Y)", or "MUST (X or Y); SHOULD X". Lacking context on
geopriv, it sounds like one of these (and it doesn't matter which).
Doesn't this mean that any SHOULD with an explicit "unless" will
need to be changed into a MUST - could you expand on this, please?
Again, I lack context here, but if the intent is as above, then they
may do.
A SHOULD X unless Y essentially means "SHOULD (X or Y)" - as Eric
says, this is probably not what the intent is, although in the case
of TLS authentication it might be a reasonable course of action. I
have to admit that if I read a "SHOULD X unless Y", given the usual
English meaning, I'd read it as the same as "MUST X unless Y", but
Eric's quite correct in pointing out the difference.
A final point is that actually phrasing it as "MUST X or Y" is
problematic since English lacks the possibility of parenthesis for
precendence - hence a stronger binding, such as MUST X unless Y, is
preferable.
Dave.
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