 The modern format for the World Championship features 16 teams in the championship group , 12 teams in Division I and 12 teams in Division II . If there are more than 40 teams , the rest compete in Division III . The teams in the championship play a preliminary round , then the top eight teams play in the playoff medal round and the winning team is crowned World Champion . Over the years , the tournament has gone through several rule changes . In 1969 body @-@ checking in all three zones in a rink was allowed , helmets and goaltender masks became mandatory in the early 1970s and in 1992 the IIHF began using the shootout . The current IIHF rules differ slightly from the rules used in the NHL . The World Championships have been open to all players , both professional and amateur , since 1977 . The IIHF requires that players are citizens of the country they represent and allow players to switch national teams provided that they play in their new nation for a certain period of time . 
