linguistic:voice_change, structural:scholar_edition, quality:corruption
Officials

A typical game of hockey is governed by two to four officials on the ice, charged with enforcing the rules of the game. There are typically two linesmen who are mainly responsible for calling "offside" and " icing " violations, breaking up fights, and conducting faceoffs, and one or two referees, who call goals and all other penalties. Linesmen can report to the referee(s) that a penalty should be assessed against an offending player in some situations. The restrictions on this practice vary depending on the governing rules. On-ice officials are assisted by off-ice officials who act as goal judges, time keepers, and official scorers.

The most widespread system is the "three-man system", which uses one referee and two linesmen. A less commonly used system is the two referee and one linesman system. This system is close to the regular three-man system except for a few procedure changes. Beginning with the National Hockey League, a number of leagues have implemented the "four-official system", where an additional referee is added to aid in the calling of penalties normally difficult to assess by one referee. The system is used in every NHL game since 2001, at IIHF World Championships, the Olympics and in many professional and high-level amateur leagues in North America and Europe.

Officials are selected by the league they work for. Amateur hockey leagues use guidelines established by national organizing bodies as a basis for choosing their officiating staffs. In North America, the national organizing bodies Hockey Canada and USA Hockey approve officials according to their experience level as well as their ability to pass rules knowledge and skating ability tests. Hockey Canada has officiating levels I through VI. USA Hockey has officiating levels 1 through 4.