Fact Check: Do NFL rules require players to stand during the national anthem?

There has been a post circulating around social media claiming that the NFL's own rules require all players and other league personnel to stand during the national anthem. It reads:"The specific rule pertaining to the national anthem is found on pages A62-63 of the NFL League Rulebook. It states:'The National Anthem must be played prior to every NFL game, and all players must be on the sideline for the National Anthem. During the National Anthem, players on the field and bench area should stand