Conduct during the national anthem is not specifically a part of the NFL rule book or players contracts. It only turns up in the league’s operations manual, which says that all players must be on the sideline for the national anthem ─ and that they “should stand at attention, face the flag, hold helmets in their left hand and refrain from talking.”

Failure to be on the field by the start of the song “may result in discipline, such as fines, suspensions and/or the forfeiture of draft choice(s),” the manual says.

The league appears not to be taking this rule too strictly, as it hasn’t punished anyone for it recently.