Another person with knowledge of the discussions told the Associated Press that the 12-hour-plus meeting at a Manhattan law firm was producing results, but that other key issues remained to be resolved, such as what free agency will look like and offseason workout rules.

The people spoke on the condition of anonymity because the talks aimed at ending the NFL’s four-month-long lockout are supposed to be confidential.

With time running short to keep the preseason intact, NFL commissioner Roger Goodell, NFL Players Association head DeMaurice Smith, eight owners, and about a half-dozen current or former players were in their second consecutive day of lengthy negotiations. They were expected to meet again today as they attempt to resolve the impasse that created the sport’s first work stoppage since 1987.

On rookie salaries, four people familiar with the talks said first-round draft picks will sign four-year contracts with a club option for a fifth year. That represents a compromise; owners were hoping for five-year contracts, while players wanted highly drafted rookies to be under a team’s control for only four years.

NFL owners have long sought to restrict the huge bonuses and salaries paid to unproven rookies, particularly those selected at the top of the draft. Quarterback Sam Bradford, taken No. 1 overall in 2010 by the Rams, signed a six-year, $78 million contract that included a record $50 million in guaranteed money.

Under the system discussed yesterday, clubs will have an option for a fifth year on a rookie’s contract for a predetermined amount based on the player’s performance.

The NFL locked out players in March, after negotiations broke down and the old collective bargaining agreement expired.

The Hall of Fame Game that opens the exhibition season is scheduled for Aug. 7 between the Rams and the Bears, who hope to be able to start training camp at the end of next week. Yet camps will not open without a new CBA in place.

US Magistrate Judge Arthur Boylan, a court-appointed mediator, ordered the sides to meet with him in Minneapolis next week, and the owners have a meeting set for next Thursday in Atlanta, where they potentially could ratify a deal.

Even once an agreement in principle on the core economic issues is drawn up, there will be more work to be done. That’s because there are certain issues that won’t be addressed in full until after the NFLPA re-establishes itself as a union - a process that might take a couple of days - and can then serve once again as a collective bargaining unit for the players.

Items that could fall under that umbrella include the league’s drug-testing program, health insurance, retired players’ pensions, and other benefits, none of which is likely to be resolved completely while the union is still dissolved.

There’s also a chance the players could pursue a lockout injunction for rookies and free agents after an appeals court ruled last week that the work stoppage could continue.

Harrison apologizes Steelers linebacker James Harrison apologized for using an anti-gay slur to refer to Goodell in an interview with Men’s Journal magazine, and said his critical statements about teammates were taken out of context.

Harrison posted a statement on his Twitter account, with the message: “This statement will be my only response to the Men’s Journal article.’’ In the article, the Steelers’ star criticized Pittsburgh quarterback Ben Roethlisberger and running back Rashard Mendenhall for their play in last season’s Super Bowl loss.

Harrison’s harshest words in the article were aimed at Goodell, whom he called a “crook’’ and a “devil.’’ He also said of Goodell, “I hate him and will never respect him.’’

Harrison did not mention those insults, but did say the anti-gay slur directed at the commissioner “was not intended to be derogatory against gay people in any way . . . I apologize to all who were offended by the remark. I am not a homophobic bigot, and I would never advocate intolerance of gay people.’’