SHOULD is evil

Having spent way too many during hours arguing with idiots who should
never have been allowed to use a computer, I would like to offer the
following text to complement section 5:

"SHOULD", "SHOULD NOT", "RECOMMENDED", and "NOT RECOMMENDED" are
appropriate when valid exceptions to a general requirement are known
to exist or appear to exist, and it is infeasible or impractical to
enumerate all of them. However, they should not be interpreted as
permitting implementors to fail to implement the general requirement
when such failure would result in interoperability failure."