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ID40-A Racked Tile Sits on the Slope
Question: What is the definition of a racked tile?
Answer: A racked tile is one that has been placed fully on the sloped part of a player’s rack. If the tile merely touches the rack or if a player taps the tile on either the top or sloped part of their rack it is not considered a racked tile. If the tile is not properly racked and someone else calls the previously discarded tile, that player would be entitled to the call and the player that did not properly rack would need to put their tile back in the same spot from where it was picked.
Source: Mah Jongg Made Easy 2020 page 19 #11