CALLING A DISCARD TO EXPOSE A BLOCK WITH SINGLES (Article 146)

Commentary: A player cannot claim a discard to expose a block of tiles with singles (i.e., 123, NEWS, 2024, 24) unless the discard is their winning tile. This also applies to pairs (i.e., 22).

Question from a player: Someone threw a 2 Crack.  I called it and exposed 2020. Another player called my hand dead.  Why is my hand dead?

Answer from the league: As soon as a tile is discarded, any player wanting that tile for an exposure may claim it, preference being given to the player next in turn, unless another player has called and exposed. To claim a discard the player must verbalize their call by saying “call,” “take, “I want that,” etc., letting the other players know that they are claiming the discard. It is permissible to say “wait” or “hold” before verbalizing a call. A caller is committed to taking a tile once the called tile has been placed on top of the rack or tiles have been exposed from the hand. The completed Pung, Kong, Quint or Sextet must be exposed on top of the rack. A Joker or Jokers may be used to complete any Pung, Kong, Quint or Sextet. An exposure may consist of all Jokers, in addition to the called natural tile

Source:  Mah Jongg Made Easy (2024 page 15 paragraph 1, inferred)

Other answers from the league:
“ Your hand is dead because 2020 consists of 4 individual tiles. It is not a kong (a group of 4 identical tiles). You may only call for a tile to complete a pung, kong, quint, or sextet, which are groupings of identical tiles. The same rule applies to NEWS. You may only call one of the tiles in NEWS if it is for mah jongg. “

“These are single tiles grouped together and you cannot use a joker or call to expose 2014.  You may only call one of these tiles if the call results in mah jongg.”

“The examples above show groups of non-identical tiles.  The only groupings in which jokers may be used are pungs, kongs, quints, and sextets which are groups of identical tiles.  Jokers may never be used in non-identical sets.  When dissimilar tiles are grouped together without spaces, these tiles are not exposable sets and may never be called except for mah jongg.”

Other sources: Mah Jongg Made Easy (2020 page 23 #10); NMJL Bulletin (1993 page 5, 2001, 2015, 2019)