|Tile types waiting||3 sided wait|
|Tiles available||11 tiles|
Sanmenchan 「三面張」 is a wait pattern, that is actually a combination of two ryanmen (open wait). This pattern utilizes a string of five consecutive numbered tiles in the hand. The exact middle tile of this string is one of the waiting tiles, while the other two hand off the edge of the string. Sanmenchan is also sometimes called a piano wait.
Just like ryanmen, this tile pattern does not reward any fu.
Sanmenchan is a powerful wait due to the large number of waiting tiles: 11 maximum possible, using any of 3-tile types. That number cannot be 12, due to one waiting tile (the middle number) already present in the hand. The waiting pattern is limited, however, to one of the three numbered suits. With suji, the waiting pattern involves one of the three mahjong intervals.
- Sanmenchan in Japanese Wikipedia