Rule 3, Section 37, Article 1 of the NFL Rule Book states "During any timeout, including an intermission, all playing rules continue in effect. Representatives of either team are prohibited from entering the field, unless they are incoming substitutes, or team attendants or trainers entering to provide for the welfare of a player, and any game-type activities are prohibited on the Field of Play. The Head Coach may enter the field to check on the welfare of a player who is injured, but no assistant coach may enter the field."