Wall kick
A wall kick happens when a player rotates a tetromino when no space exists in the squares where that tetromino would normally occupy after the rotation. To compensate, the game sets a certain number of alternative spaces for the tetromino to look.
Koryan as well as Jagorochi researched the SRS system thoroughly and made diagrams of how SRS finds wallkicks.
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The complete system for a number of Tetris games exists in wktables.c within open-source Lockjaw.