The rest of the rule is than no player can go out of bounds and return and be the first player to take control of the ball (via catch, fumble, punt reception, etc.)
In addition, a player that goes out of bounds must attempt to get back in bounds as soon as possible. Running behind the bench, for example, is designated as a delay of game or a personal foul, depending on how blatant it is.
I have been following this game since 1969 — I know all the rules.