1. The only offside line is the attacking blue line. Skaters of the attacking team cannot cross this line before the puck without incurring an offside. (See Rule 81-1 for exception)

2. The entire width of the blue line is considered part of the zone the puck is in.

3. If the puck is outside the attacking blue line, it is not considered inside the attacking zone until it is completely over the blue line.

4. If the puck is in the attacking zone, it is not considered outside the blue line until it is completely over the blue line.

5. If a skater on the attacking team is inside the attacking zone and the puck is in the neutral zone, the puck is not considered in the attacking zone until it is completely over the blue line.

6. Offside is determined by the position of the skates of the attacking team at the attacking blue line in relation to the puck. An attacking skater is offside when both skates are completely over the blue line in the attacking zone before the puck is completely over the blue line. This includes the three-dimensional position of the puck. If the puck is in the air directly above the plane of the blue line before any attacking skater, the play is onside.

7. Skaters’ skates are interpreted only in two dimensions. Any skate that is in the air is considered not on any side of the blue line until it touches the ice.

8. To be onside, a skater may have one skate inside the blue line as long as one is on or outside the blue line touching the ice.