In NHL rules, the periods are 20 minutes long.

The NHL rules are slightly different from those used in Olympic hockey.

A new NHL rule added in the 2005-2006 season prevents a team from changing their line after they ice the puck.

NHL rules restrict the total number of players per game to 18, plus two goaltenders.

He had to wait for a month for an NHL rule to be changed before he could play.

The actual game five used NHL rules, as it was considered a replay of game four.

The NHL rules are slightly different from those used in Olympic ice hockey over many categories.

Under current NHL rules, this plays an important tiebreaking role.

Fights were included in the game, but the rules of such greatly differed from NHL rules.

NHL rules forbid goaltenders from participating in play past the center line, so a goal by a goalie is possible only under unusual circumstances.