what is a sideline warning

A sideline warning is a cautionary measure taken by game officials in football when a coach or non-player personnel from one team steps onto the field during a play or when players and coaches are not staying far enough away from the field during a live play. The restricted area is the space between the sidelines and the coaches box and team area. The first infraction usually results in a warning, with repeated offenses punished by a loss of yardage. In college football, the first offense of a sideline infraction results in a warning, with no yardage penalty. After a few years, the rule was changed to assess a five-yard penalty for the first offense. Now, the NCAA has returned to the warning for the first infraction. The referee signal for a sideline infraction penalty is crossing hands behind their lower back while facing the press box. A sideline warning is given to keep the sidelines clear so that the play on the field is not affected. If a coach physically interferes with play or the actions of an official, they will be called for unsportsmanlike conduct and assessed a 15-yard penalty, even if it is their first offense.