Foot swinging past the rubber:
OBR - 8.05
If there is a runner, or runners, it is a balk when --
(a) The pitcher, while touching his plate, makes any motion naturally associated with his pitch and fails to make such delivery;
Rule 8.05(a) Comment: If a lefthanded or righthanded pitcher swings his free foot past the back edge of the pitcher’s rubber, he is required to pitch to the batter except to throw to second base on a pick-off-play.
FED - 6-2-4
Balk. If there is a runner or runners, any of the following acts by a
pitther while he is touching the pitcher's plate is a balk:
f. failing to pitch to the batter when the entire non-pivot foot passes behind
the perpendicular plane of the back edge of the pitcher's plate, except when
feinting or throwing to second base in an attempt to put out a runner.
NCAA - 9.1-B
(3) When the pitcher starts the delivery from the set position and the
entire free foot or any part of the stride leg breaks the plane of the
back edge of the pitcher’s rubber, the pitcher is committed to throw
or feint a motion toward second base or pitch to home plate.
PENALTY—For violations of 1, 2 or 3, a “balk” shall be called.
Posted just to help with the understanding of the discussions.