Occurs when an infringement has taken place and the referee has not awarded a penalty kick, drop-out or a play-the-ball. The six forwards from both teams pack into a three-two-one formation on each side of the scrum, and aim to gain an advantage by pushing the defensive scrum back into its own territory as far as possible. Once there is a clear tunnel between the two front rows, the ball is played straight into the middle by the scrum-half of the non-offending team. The forwards then back-heel the ball to the scrum-half, who gets play under way again.