NEW YORK -- The NHL and NHL Players' Association appear to be inching slowly towards a deal to salvage the hockey season.

But they still have plenty of ground to cover.

With collective bargaining talks reaching a critical point, the sides have quietly exchanged new proposals and are committed to picking up talks again on Friday. It will be the fourth straight day they've sat across from one another during an intense week of bargaining.

"We have work to do," commissioner Gary Bettman said Thursday night.

Little is known about exactly where talks stand.

Sources told The Canadian Press that the NHL responded to a pair of union proposals on Thursday and one suggested it was a good sign the sides still planned to keep negotiating. On Wednesday night, the NHLPA tabled new offers regarding revenue sharing and the league's "make whole" provision, with the union suggesting a system where the players' share in revenue reaches 50-50 in the third year of the deal.

That still amounts to a major financial concession -- as much as $1 billion over the course of the deal -- from the current split of 57-43 in favour of the players.

As a result, the NHLPA is asking for an improved revenue sharing system and isn't eager to see changes made to rules governing contracts, many of which were won in the last round of negotiations.

Bettman and Donald Fehr, the NHLPA's executive director, were extremely careful not to reveal much about discussions after meeting for more than five hours on Thursday.

"I'm not going to characterize (the talks) except to say, as I have before, that it's always better when you're meeting than when you're not," said Fehr.

With all regular-season games cancelled through Nov. 30, negotiations have reached a critical and delicate stage. Ten days will be needed from the time an agreement is struck until the season starts and there is still hope among the parties that a shortened schedule could begin by Dec. 1.

For that to happen, signs of progress need to emerge soon -- something neither side is entirely sure will happen.

"Collective bargaining is a process and it has peaks and valleys and ebbs and flows and it's very tough to handicap," said Bettman.

The underground meetings became slightly more public on Thursday, when reporters managed to track the sides down at the midtown Manhattan offices of Proskauer Rose. That's the law firm that employs NHL lead counsel Bob Batterman and it is located across the street from the office building where the 2004-05 CBA was hammered out.

With negotiations taking on a more urgent nature, the sides have completely turned down the rhetoric. Fehr indicated it was important not to comment on what was being discussed because so much information is now being traded back and forth across the table.

It was one issue where the sides had already found agreement.

"I'm not going to discuss the negotiations or the substance of what we're talking about," said Bettman. "I really don't think that would be helpful for the process."

The commissioner was speaking only a few blocks from Madison Square Garden, where the Rangers had originally been scheduled to face the Minnesota Wild in one of 11 games scheduled for Thursday night.

Interestingly, a key gap that remains between the sides is figuring out how contracts can be "made whole" now that a full season won't be played. Players were paid $1.833-billion out of the $3.3-billion generated in revenue last year, but the overall pot is bound to shrink now that a shortened schedule is the best-case scenario for 2012-13.

Despite not seeing eye-to-eye on the important issues, the key negotiators seem intent on trying to hammer out a deal.

They have met for a total of about 25 hours over the last week, starting with an informal eight-hour session between deputy commissioner Bill Daly and NHLPA special counsel Steve Fehr in Chicago on Saturday. Larger groups that included owners and players spent more than 17 hours at the bargaining table over the last three days.

Both sides have cleared their schedules -- Daly cancelled an appearance at Parliament Hill in Ottawa on Thursday -- and they'll continue to do so as long as there is some momentum to be found in negotiations. With the lockout approaching eight weeks, there is a possibility they might continue negotiating right through the weekend.

"We're in a process now with a series of meetings," said Bettman. "Hopefully, it leads us to the right place."