What calls for a false start in football?

Usually false starts are called if the player flinches even a little bit. But often the center may point at different things and make movements. In today's FloridaLSU game, the center would tilt his head pre-snap several times and not be penalized. However, when the defensive player jumped when the center tilted his head later in the game, the center was penalized. What's the definite rule on false starts?What calls for a false start in football?
I saw that in the FLA-LSU game. That center SHOULD HAVE been called every time for that. The difference might be that every conference has different refs, and maybe different conferences have different interpretations of the rules. (regardless, that was false start by FLA)What calls for a false start in football?
The Center is really the leader of the Offensive Linemen and calls adjustments like was seen in the Florida-LSU game. Centers are usually called for moving the ball and trying to get the defense offsides.


However, once the line is set the center can be called.
Usually the center has a little more room of moving other than the guard and takle. But it is after the player gets in his position you can not move.
The Center is allowed to move Slightly if he's in shotgun... but not on a regular snap... also the lineman may point and call out blitzes so the line knows what protection to do!