When an attacking player leaves the offensive zone due to a pending delayed offside call by the linesman.
This is often called the tag up rule or tag up offside. An attacking player is immediately called offside when entering the offensive zone with the puck after a teammate has already entered the zone before him. An offside is also called immediately if a player skates into the offensive zone ahead of the puck and then receives a pass from a teammate. However, if an attacking player skates into the offensive zone before the puck, but the puck is shot into the zone and retrieved by a defending player the play is considered to be a delayed offside. This is because the attacking team is no longer in possession of the puck and the defending side now has a chance to move it out of their own zone. All players on team that shot the puck into the attacking zone must now retreat into the neutral zone to nullify the delayed offside call. As soon as all players have retreated into the neutral zone the play is now considered onside and they can reenter the offensive zone.