Kjetil Torgrim Homme wrote:
On Thu, 2006-07-27 at 15:01 +0100, Alexey Melnikov wrote:
 
Kjetil, there is very much 50/50 split between people who want to change 
the SHOULD to MUST and people who want to keep it as SHOULD or even 
relax it.
RFC 3028 used SHOULD. Considering even split (and good technical 
arguments on both sides) I don't see any reason to change it to anything 
else.
   
yes, it says that in general:
  Implementations SHOULD prohibit reject when used with other actions.
but it also calls the explicit combination we're talking about
"invalid":
  Implementations might
might is non normative here. I certainly wouldn't interpret it as "MUST".
even go so far as to ensure that scripts can
  never execute an invalid set of actions (e.g., reject + fileinto)
  before execution, although this could involve solving the Halting
  Problem.
I don't think changing it to a MUST is changing the spec, it's just
clarifying it.
 
I think part of the reason why we have this discussion now is because 
the text you quoted is sufficiently ambiguous.