"In ice hockey, a play is offside if a player on the attacking team enters the offensive zone before the puck, unless the puck is sent or carried there by a defending player. When an offside violation occurs, a linesman will stop play. A faceoff is then held at a neutral ice spot closest to the infraction to restart play. ...
The National Hockey League (NHL) and International Ice Hockey Federation (IIHF) apply similar rules for determining offside. A player is judged to be offside if their skates completely cross the blue line dividing their offensive zone from the neutral zone before the puck completely crosses the same line. In both organizations, it is the position of a player's skates that are important. They cannot use their stick or other part of their body to remain onside. The lone caveat to this rule is that an attacking player's skates may precede the puck into the attacking zone when they are skating backwards and if they are in control of the puck." [Offside (ice hockey). Wikipedia]
The ice hockey tactic diagram example "Offside (ice hockey)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Hockey solution from the Sport area of ConceptDraw Solution Park.