Table Reading
How to read public discards.
The discard pool is shared information. It tells you what is gone, what is risky, and when your own target hand needs to change.
American Mah Jongg
Dead Tiles
If all copies of a needed tile are visible in discards or exposures, the hand line that needs that tile cannot complete naturally.
Danger Tiles
A discard becomes dangerous when it matches exposed groups or likely target lines for another player.
Timing
Early discards can be exploratory. Late discards are more meaningful because players have had time to commit to a target.