Definition
369 is the section of the card built from the numbers three, six and nine, in patterns that combine them across one or more suits.
Because only three numbers are involved, it pairs naturally with dragons and with jokers. A deal with several threes, sixes and nines and little else is a 369 deal.
Read the full guide: How to Read the Mahjong Card: The Notation, Decoded.
See it on real tiles: the coach reads any hand and names its direction, free, at the free read. Members get the coach on call for their own games.
More terms: Pung, Kong, Quint, Pair, Charleston, Blind pass, Courtesy pass, Joker.