The exchange of proposals between the NHL and NHL Players Association this week is a positive sign – at least they’re talking – but the two sides remain far apart. If the NHL is headed for another lockout – a the third in 18 years, eight years after an entire season was lost – the timeline for the winter is starting to come into focus.

The current collective bargaining agreement with the NHLPA expires on Sept. 15, and NHL commissioner Gary Bettman has indicated the league will lock out the players rather than continue to play under the old agreement.

There are many issues being debated, from contract lengths to revenue-sharing among teams to participation in the Olympics, but the essential disagreement is over what share of league revenue goes to the players. For the last eight years, that figure has been 57 percent. The owners’ first proposal set that at 46 percent – 43 percent, by the union’s estimation. Eventually, they’ll settle somewhere in the middle.

Based on the fall of 2004, here’s what is likely to happen next if there is no agreement in the next two weeks:

The Hurricanes are scheduled to open training camp on Sept. 22. Along with the announcement that the league has locked out the players, the league will announce the cancellation of training camps, some or all preseason games and possibly regular-season games as well.

If the same protocol applies as eight years ago, NHL players who don’t need to clear waivers to go to the minors will be assigned to the AHL. Last time around, that included Eric Staal and Cam Ward. This time, it might include Justin Faulk, Jeff Skinner and Jeremy Welsh (if he signs before Sept. 15; he’s a restricted free agent). Some NHL players will sign temporary deals in Europe.

A deal could happen at any point, but there are two key pressure points that could drive compromise. One is Opening Night on Oct. 11. Both sides would benefit if the season starts on time. To realistically start on Opening Night, teams would need at least two weeks of training camp. So a deal would have to be reached, in principle at least, by about Sept. 23. (In 2004, Bettman wiped out Opening Night when he announced the lockout on Sept. 15, but the mood was far less conciliatory then.)

After that, with the owners once again geared down for the long haul, the next potential deadline is the Winter Classic, this year to be played by the Detroit Red Wings and the Toronto Maple Leafs at Michigan Stadium. While the NHL is guaranteed its U.S. TV money from NBC during the lockout – giving the owners a reason not to settle quickly – it won’t want to give up the exposure of the popular Jan. 1 game that has crossover appeal in the United States.

For the season to begin on Jan. 1, two weeks of training camp would be necessary, at the minimum; that makes Dec. 15 the deadline for a deal – and if we get that far, the moment when the entire season will hang in the balance. In 1994-95, a deal was reached on Jan. 11, in time to play a compressed 48-game season starting nine days later.

The owners broke that time, giving up on a salary cap to save the season. Ten years later, the owners held firm and the players finally agreed to a deal in July that included a salary cap. This time around, neither side seems inclined to budge – the owners, having learned they can sit out an entire season and still win; the players, who feel like they gave the owners everything they wanted last time and are now being asked to give up more.

Once the Winter Classic is lost, there’s really no reason for the owners not to pull the plug on the rest of the season. They’ve shown before they’re willing to use that threat as leverage, and as Bettman said last week, “We recovered well last time because we have the world’s greatest fans.”

luke.decock@newsobserver.com, Twitter: @LukeDeCock, (919) 829-8947