The ball can be kicked in any direction, but must be passed backwards. Players attempt to stop the opposition running the ball by tackling them. Rucks form when at least one player from each team is on their feet and the ball is on the ground. Mauls are formed when the ball carrier is held by at least one of the opposition and a teammate is also bound to them. Players can compete for the ball at tackles, rucks and mauls in accordance with the laws. Scrums are used to start play after minor infringements (knock-ons and forward passes) and when the ball becomes unplayable. All eight members of the forwards must be involved in the scrum provided the team still has all fifteen players present. Players involved in the scrum stay bound to each other and the opposition until it is finished and the rest, except the scrum-half, must be positioned at least five metres back. The two teams push against each other and the hookers strike for the ball once the scrum half puts the ball into the "tunnel" (gap between the two front rows). The scrum half must put the ball straight down the centre of the tunnel, if the scrum half deliberately puts the ball in at an angle to his second rows feet, (feeding the ball), the opposition are awarded the 'put in'. Lineouts are used to restart play when the ball has crossed the sidelines. Players form two parallel lines perpendicular to the sideline and the team that did not put the ball out throws it straight down the middle. Players in the line-out can be lifted by teammates as they attempt to win the ball. The early rules of football were determined by pupils before the game, with the legality of carrying or running with the ball often agreed shortly before commencement. The first set of written rules were published by pupils at Rugby School in 1845 and while a number of other clubs based their games on these rules there were still many variations played. The Football Association intended to frame a universal code of laws in 1863, but several newspapers published the 1848 Cambridge rules before they were finalised. The Cambridge rules included rules for "running with the ball" and "hacking" (kicking an opponent in the shins) which were not part of the Football Association draft. They decided not to include those rules in their release, causing a number of rugby clubs to break away from the Football Association. The rules for playing rugby still differed between clubs, so in 1870 twenty one clubs formed the England-based Rugby Football Union (RFU) and standardised the laws of the game.