In the Japanese Mah Jong the rule of Sacred discard is often used. The use of this rule requires that the discarder is marked somehow on melded sets.
If the extended information is enabled, Four Winds displays for each melded set the discarder by using a wind marker. The discarder is mentioned in the message line, as well. In addition, for discarded tiles, the ones that were claimed are shaded and the claimer is shown in the message line.
Note: The option is not available if the discards are placed face down on the board.
Related topics:
Using five sets
Number of rounds
Round wind sequence
Dead Wall
Specifying how discards are placed on board
Charleston
Pass deal after East's win