The following conventions or treatments are categorised as
(a) Any opening bid of two clubs through to three spades that:
(i) could be weak (may by agreement be made with values below
average strength); AND
(ii) does not promise at least four cards in a known suit.
(iii) The bid always shows at least four cards in a known suit if
it is weak. If the bid does not show a known four card suit it
must show a hand a king or more over average strength.
(Explanation: Where all the weak meanings show at least four
cards in one known suit, and the strong meanings show a hand
with a king or more above average strength, it is not a Brown
(iv) An opening bid showing a weak two in either major,whether
with or without the option of strong hand types
(b) An overcall of a natural opening bid of one of a suit that
does not promise at least
four cards in a known suit.
EXCEPTION: A natural overcall in no trumps.
(c) Any ‘weak’ two-suited bids at the two or three level that
may by agreement be made with three cards or fewer in one
of the suits.
(d) Psychic bids protected by system or required by system.
(e) None of the foregoing restrictions pertain to
conventional defences against strong, artificial opening bids or
defences against ‘Brown Sticker’ or HUM conventions.