Three-on-three overtime is getting the thumbs up from NHL general managers, although a format decision and final approval are still needed.

GMs agreed to recommend some type of three-on-three beginning next season but are still debating whether to add time to the extra session or begin overtime three-on-three instead of four-on-four.

The recommendations will go to the joint NHL/NHLPA competition committee, which meets in June and must approve any rule changes.

That committee will also consider the other recommendation from general managers of instituting a coach's challenge system for goaltender interference and delay of game penalties for the puck going over the glass.

If it goes through, coaches will be able to challenge goalie interference only on goals scored and only if they have their timeout left.

Referees will be able to consult with the situation room in Toronto to make what commissioner Gary Bettman deemed "the better call" on goalie interference, which is often a case of judgement.

Puck over the glass penalties can be challenged, and those plays would go to the situation room.

In addition to the competition committee, the NHL's board of governors must sign off on plans before anything changes.