I know it is on the bench but I'm not sure for the squat
This is taken from the IPF rulebook, see rule 4 in particular:
Causes for disqualification of a Squat:
- Failure to observe the Chief Referee’s signals at the commencement or completion of a lift.
- Double bouncing at the bottom of the lift, or any downward movement during the ascent.
- Failure to assume an upright position with the knees locked at the commencement or completion of the lift.
- Stepping backward or forward or moving the feet laterally. Rocking the feet between the ball and heel is permitted.
- Failure to bend the knees and lower the body until the top surface of the legs at the hip joint is lower than the top of the knees, as in the diagram.
- Contact with the bar or the lifter by the spotter / loaders between the Chief Referee’s signals in order to make the lift easier.
- Contact of the elbows or upper arms with the legs. Slight contact is permitted if there is no supporting that might aid the lifter.
- Any dropping or dumping of the bar after completion of the lift.
- Failure to comply with any of the items outlined under Rules of Performance for the squat.