of kick tries. Ability of defensive team to score after gaining possession on a turnover: US college, CFL, AAF, Texas high school: Can advance the ball upon gaining possession; if it scores a touchdown, it will satisfy the condition of each team having a chance to score and thus end the game. US and BC high school (except Texas): Possession ends immediately. Each team receives one charged timeout per overtime procedure except in the CFL and AAF, which allow(ed) no timeouts in overtime. If the score remains tied at the end of an overtime procedure, another procedure follows (except as noted below), with the team that had the second possession in the previous procedure having the first possession of the next procedure. Limit on number of overtime procedures: US college and high school: No limit; procedures continue until a winner is decided (some states limit the number of procedures or outlaw it altogether for games below the high school varsity level). CFL: In regular season games, maximum of two procedures, with the game declared a tie if it remains level. In postseason games, procedures continue until a winner is decided. AAF: Same as CFL, except that only one procedure was allowed in regular-season games. The league folded without holding any playoff games. One aspect of the AAF overtime rules was unique to that league—field goals were prohibited during overtime. The NFL overtime is a modified sudden-death period of 15 minutes, for playoff games only; since the 2017 season, overtime periods in the preseason and regular season are 10 minutes, as part of an overall effort by the NFL to speed up games and reduce their length. If the team that receives the opening kickoff scores a touchdown, or the defensive team scores a safety, the game ends at that point. If the receiving team scores a field goal, the game continues with the scoring team kicking off, and the scored-upon team having a chance at possession. If that team scores a touchdown, or loses possession, the game ends; if it scores a field goal, overtime continues, with the next score by either team ending the game. In the regular season, if a game remains tied after the 10-minute period, it is declared a tie. In postseason games, there are multiple 15-minute periods until a winner is decided. The overtime protocol of the second XFL, currently on hiatus, was significantly different