Barry Leiba wrote:
While using SHOULD here might be fine, not describing valid reasons for
violating the SHOULD when they are known in advance is a very bad
thing. I
always prefer documents that explain background/motivation.
...
I read this as allowing an implementation to ignore :message and/or
the Subject
URI header unconditionally. Is this something we actually want to
encourage? I
certainly wouldn't want to.
A much better approach is to at least explain what are valid reasons for
violating the SHOULD and optionally use MUSTs.
No, no, no, no!
Yes, if we know a reason why you might want to vary from what we
recommend, it's always a good idea to explain that. But that's a side
issue, and it doesn't really matter.
Actually, it is the only thing that matters to me in this case.
I can live with either SHOULD or MUST, but now that I know about Arnt's
issue, I can't live without its description ;-).
The fact that we can't think of why you might want to... doesn't mean
that we should forbid it.
Second, using SHOULD is *not* "encouraging" contrary behaviour. Quite
the opposite: it's saying that if you don't have a damned good reason
for doing otherwise, this is the course you'd better take.
Well, if I see SHOULD in the spec *and* there is no explanation why
SHOULD is there and it is very difficult for my implementation to
conform to the SHOULD, then I don't feel bad about violating it.
But anyway, let's stop discussing this. It is not that important. And if
you turn out to be wrong in the future, then I will point this out ;-).