Black 30 is bouncing the ball in the low post whilst being guarded by White 9. This player, White 9, has a legal guarding position (facing the opponent with both feet on the floor) when a contact occurs and the referee calls an offensive foul. Article 33.12 The principle of verticality (cylinder principle) applies also to post play. The offensive player in the post position and the defensive player guarding him must respect each other's rights to a vertical position (cylinder). It is a foul by an offensive or defensive player in the post position to shoulder or hip his opponent out of position or to interfere with his opponent’s freedom of movement using extended arms, shoulders, hips, legs or other parts of the body. Article 33.15 Pushing is an illegal personal contact with any part of the body where a player forcibly moves or attempts to move an opponent with or without the ball. Outcome: Correct decision from the referees. Black 30 extended his arm outside his cylinder and pushed-off his opponent with his forearm. The ball shall be awarded to the White team for a throw-in from the place closest to where the infraction occurred.