Calling a Tile While Playing a Concealed Hand (Article ID 22)
Abstract: The letter “C” to a the right of the hand, indicates one cannot call to expose tiles during the game. When playing a concealed hand, you can only call a tile that results in mah jongg.
Question from a player: If you are playing a concealed hand, can you call for the 14th tile if it results in mah jongg?
Answer from the NMJL: “Calling a tile for mah jongg is the only time you may pick up a discard when playing a concealed hand.”
Source: Mah Jongg Made Easy (2020 page 15, para. 6); National Mah Jongg League Bulletin Q&A (2015) https://www.nationalmahjonggleague.org