A brown sticker convention (BSC) is a convention which requires special defence, thus not allowed in most events, except some more advanced events. The only kind of conventions which is restricted even more than brown sticker conventions is highly unusual methods.
Most either-or methods are classified as brown sticker.
More formally, the following treatments or conventions are classified as brown sticker:
- An opening bid between 2♣ and 3♠ that could be weak and does not promise at least four cards in a known suit.
- An opening bid which is either weak or strong, and promises at least four cards in a known suit when it is weak, is not a brown sticker opening.
- Exception: Multi two diamonds
- An overcall over a natural 1-level suit opening that does not promise at least four cards in a known suit.
- Exception: A natural NT overcall.
- Exception: Any cue-bid which shows a strong hand.
- Exception: A jump cue-bid in an opponents known-suit that asks the partner to bid with a stopper in that suit.
- A weak two-suited bid at the 2 or 3-level which may be made with 3 cards or fewer in one of the suits.
- Systematic psychs.
Brown sticker restrictions are not applied on defenses on brown sticker conventions or highly unusual methods.