Contract negotiations between the National Football League and the striking NFL Players Association continued here today amid signs that the union is willing to modify its wage scale demand to achieve a settlement.

In addition, it was learned tonight that all noneconomic issues appear to be settled. Sources said Ed Garvey, the union's executive director, and Dan Rooney of the Pittsburgh Steelers, a member of the NFL Management Council's executive committee, met during the evening about the remaining issues, free agency and, particularly, the union's demand for a wage scale. Sources said the meeting lasted about an hour.

Mediator Sam Kagel pointed out earlier in the day that "everything (economic and noneconomic issues) is all mixed together. These lines of demarcation are rather meaningless in collective bargaining negotiations."

The wage scale remains at the heart of the dispute, with negotiations not yet addressing the players' demand that a trust fund be set up to pay salaries on a seniority-based scale with performance incentive bonuses. That is a concept the NFL says it opposes and the union remains committed to.

But union sources said it could be modified; one possibility would be by exempting a particular class of players--the superstars of the game, for example--from the scale; these players would instead negotiate directly with the owners. The union also says the numbers in its proposal are negotiable.

In a related development, it was learned that Garvey met this morning with Ted Turner, chairman of the Atlanta-based Turner Broadcasting System, to discuss the possibility of forming a players' league if the NFL calls off the season because of the strike. The two met at a nearby private airport after Turner arrived in a jet from Atlanta for today's NFLPA all-star game at RFK Stadium.

Union sources said Turner, who is televising the union all-star games, was enthusiastic about funding such a league in exchange for television rights. Robert Wussler, executive vice president of Turner broadcasting, confirmed that TBS had discussed such a possibility.

"Obviously, we have talked about contingency plans down the road," he said from Atlanta. "We are looking at the possibility in the event of an announced long-term walkout."

Tentative plans call for teams to be formed in all or most NFL cities. The league would attempt to duplicate the current NFL schedule as much as possible.

Next year, if there is still no settlement, union sources said the players would attempt to play a full season of league games; they would almost certainly face a vigorous challenge from the NFL. Speaking for TBS, Wussler said there had been "no discussion beyond this year . . . It is difficult for me to envision a strike that could last beyond a season."

The union said the players' league games are only an option if the NFL carries out its threat to call off the season. NFL Commissioner Pete Rozelle has said the owners believe they need at least 13 games to constitute a credible season, but later said some owners would accept a 12-game season.

Turner, interviewed at RFK Stadium in Washington before the first NFLPA all-star game, said, "I am committed to the NFLPA until it (the union strike against the NFL) is all resolved." Turner Broadcasting pays the union $500,000 for each all-star game.

Turner said TBS, seeking advertisers for the current NFLPA all-star games, went to every firm that has sponsored NFL games. Only Chrysler and Wang were interested.

"We know the networks threatened reprisals if they advertised (this game)," said Turner. "They (the NFL) are trying to quash the NFLPA . . . They'd be advertising if the game was on CBS."

Wussler said that the union probably will keep four basic all-star teams for now and augment them with fresh players. He said a decision also would be made this week on whether to have one or two games every weekend as long as the strike lasts and the season is not canceled, although it is likely that next week there will be two.

As the strike entered its 27th day, negotiators were still concerned with noneconomic issues, although sources said this process was nearing completion.

Currently the NFLPA is demanding that the NFL contribute $1.6 billion to its wage-scale trust fund over a four-year period. The NFL says it's willing to pay out that sum over five years but it wants to retain the current system of individual negotiations.

This was the fourth consecutive Sunday the strike has shut down the NFL. Today's negotiations did not get under way until early this afternoon, in part to permit Garvey and Jack Donlan, the executive director of the NFL Management Council, to attend mass at a Roman Catholic church near here.

Kagel, in his daily briefing with the news media, said the discussions so far have concerned "some 20 or more subjects which constitute part of the collective bargaining agreement" and that the talks would continue into the night.

In another development, Rozelle said a regular meeting of the NFL owners originally set for Tuesday has been postponed until the strike is over.