In what could be a sign of an end to the ongoing NFL referee lockout, the league and the NFL Referees Association have settled at least one of their issues, with the union agreeing to allow backup crews.

The two parties agreed on 21 backup officials that will be placed in a developmental program, according to, but they will not work games and cannot be subbed out.

Many believed the main cause of the lockout was a contention over pension benefits and how much the NFL would agree to pay into the plan, with a figure of $3 million as a target for the referees. The league also reportedly wants to switch the referee's benefits to a 401(k) plan.

Yet the league has pushed for the referee development program for quite some time, and it was believed to be their main sticking point throughout the negotiations, according to Sports Illustrated’s Peter King.

There has been no movement on the pension plans yet, with owners increasing their role in the negotiations and a federal mediator sitting in on talks.

The lockout began in the preseason, and has now spilled over into the regular season for three weeks. Replacement referees took over and have caught the ire of fans and the media with questionable calls in many games.

Meetings may have taken on more of a sense of urgency since Monday night’s highly controversial ending to the Seattle Seahawk’s 14-12 win over the Green Bay Packers.

The replacement officials ruled that Seattle receiver Golden Tate and Packers safety M.D. Jennings simultaneously caught the ball in the end zone on the game’s final play, and awarded the Seahawks the touchdown and the win as a simultaneous catch goes to the passing team.

In a statement Tuesday, the NFL said the officials made the correct call of a simultaneous catch, but that Tate should have been called for offensive pass interference on the play.