Concealed 1112345678999 in one suit, plus any duplicate.
Sources genuinely differ between 10 and 13. We score a flat 10, with the tournament books. The full comparison
A concealed hand in one suit holding 1-1-1, 2, 3, 4, 5, 6, 7, 8, and 9-9-9, plus any one tile of that suit to finish. It is ten faan.
The shape waits on all nine tiles of the suit at once, which is where the name comes from. It must be concealed throughout.
You do not build this so much as recognise it. It requires a very heavy one-suit start and no claiming at all. If you find yourself close, the compensation is that the wait is the widest in the game: any of the nine tiles completes it.
Claiming a discard along the way. The hand must be concealed, and one claimed set ends it. What you are left with is usually still Pure One Suit at seven faan, which is not a disaster, but it is three faan lost for nothing.
It contains Pure One Suit and Concealed Hand by definition. Both score with it, so the hand lands at or near the limit. Winning on your own draw adds Self Draw on top.
Does it have to be concealed?
Yes. Any claimed set ends the pattern, leaving you with Pure One Suit.
What does it wait on?
All nine tiles of the suit. It is the widest wait in the game.
Do honours break it?
Yes. Every tile must be from the single suit.
Play Mahjong Winds
Every win shows its faan line by line, using the table on this page.