Commitment to Discarding a Tile (Article ID 18)
Abstract: Once a player names or discards a tile they cannot change their mind and discard a different tile or use it in a joker exchange.
Question from a player: A player has announced a discard but has not placed it on the table. May she change her mind? May she instead exchange it for an exposed joker on some else’s rack?
Answer from the NMJL: “Once a tile is named or discarded, the discarder cannot take it back. Down is Down. “
“Once a symbol tile has been named or discarded, it cannot be taken back to make an exchange for a Joker. Down is Down.”
Source: Mah Jongg Made Easy 2020 page 19 #7 , page 23 #5
Other Answers from the NMJL:
“Once a tile has been named it is considered a down tile and player cannot take the tile back. If a tile is shown face up on the table, even if it is not named, it is a down tile and cannot be taken back.”
“Once a tile is discarded and named it cannot be taken back by the discarder. Down is down.”
“Once a player has announced the forthcoming discard, it is the same as the tile were placed on the table. In this case, it is too late for this player to redeem a joker on someone’s rack.”
“Once a tile has been announced (even though the player has not placed the tile down on the table), it is considered a down tile. If a tile is placed on the table and not announced yet, that too is considered a down tile.”
“Once a tile has been announced (even though the player has not placed the tile down on the table), it is considered a down tile. If a tile is placed on the table and not announced yet, that too is considered a down tile. Down is down. Discarder cannot change his/her mind.”
“You are committed to discarding a tile once it is fully named or the tile has been placed on the table.”
Source for other answers: National Mah Jongg League Bulletin Q&A (1982 page 4, 1983 page 4, 1984, 1988 page 5, 1989 page 5, 1999 page 6, 2003, 2008, 2010, 2011, 2012, 2014, 2015. 2017, 2018) https://www.nationalmahjonggleague.org