flags total) One flag post positioned 2 metres outside of both of the sidelines, in line with the halfway line (2 flags total) Goalposts Rugby goalposts are H-shaped and are situated in the middle of the goal lines at each end of the field. They consist of two vertical poles (known as "uprights"), generally made of steel or other metal but sometimes wood or a plastic, apart, connected by a horizontal "crossbar" above the ground. The minimum height for posts' uprights is , with taller posts generally seen. The bottom parts of each upright are generally wrapped in purpose-made padding to protect players from injury when coming into contact with the posts and creating another opportunity for sponsors. If an attacking player grounds the ball onto the base of the upright or post padding, a try will be awarded as the base of the upright is considered in-goal. Match structure At the beginning of the game, the captains and the referee toss a coin to decide which team will kick off first. Play then starts with a dropkick, with the players chasing the ball into the opposition's territory, and the other side trying to retrieve the ball and advance it. The dropkick must make contact with the ground before kicked. If the ball does not reach the opponent's line 10 meters away, the opposing team has two choices: to have the ball kicked off again, or to have a scrum at the centre of the half-way line. If the player with the ball is tackled, frequently a ruck will result. Games are divided into 40-minute halves, with an intermission of not more than 15 minutes in the middle. The sides exchange ends of the field after the half-time break. Stoppages for injury or to allow the referee to take disciplinary action do not count as part of the playing time, so that the elapsed time is usually longer than 80 minutes. The referee is responsible for keeping time, even when—as in many professional tournaments—he is assisted by an official time-keeper. If time expires while the ball is in play, the game continues until the ball is "dead", and only then will the referee blow the whistle to signal half-time or full-time; but if the referee awards a penalty or free-kick, the game continues. In the knockout stages of rugby competitions, most notably the Rugby World Cup, two extra time periods