[mycroft]

Hrothgar, any regulatory agency that looks at 2 and can't work out for themselves that it's equivalent to 1 and, if 1 isn't allowed, neither is 2, is, as you say, flawed. In other words, everything except your ultimate conclusion I agree with.

Anybody who tried 2, knowing that 1 is not allowed, should be treated with exactly the contempt anyone else who plays games like that usually is.

I do not believe that exclusion requires mention explicitly; simply the obvious fact that exclusionary schemes that are equivalent to an inclusionary description are regulated equivalently will do.

For instance, for normal bridge values of "promises 5 spades", 6322 meets 2, and not 1, and reasonably is treated differently (which is where we can say that 2C "5+ clubs, *if only 5*, promising a 4 card major" is natural, where 2S "promises 5-4 in spades and a minor" (or "exactly 5 spades, unbalanced, not 4 hearts", if someone wants to try that one on) is not).

[campboy]

I think the key point is, as mycroft suggests, that even if a bid which shows n+ in the suit bid with some shapes excluded is natural it does not follow that a bid which is the same except for denying more than n in the suit is also natural. After all, would anyone think you are permitted to play a 1♣ opening as showing exactly 3 clubs in a balanced hand, just because a standard American 1♣ is "natural"? Likewise "2♥=unbalanced with 5+ hearts" is natural but "2♥=unbalanced with exactly 5 hearts" is not.