The crush system in Tekken 7, allows certain moves to make the character not get hit by high or low attacks, called high crush and low crush respectively. It works by the move causing the character to enter crouch or jump after a number of frames from the startup of the move.
HIGH CRUSH
High crushing moves will evade highs by causing the character to crouch during the move. This is might be referred to in frame data as tc (technically crouching) or cs (crouching state).
LOW CRUSH
Low crushing moves will evade lows by causing the character to jump during the move. This is might be referred to in frame data as tj (technically jumping) or js (Jumping state).