MINNEAPOLIS — A $4 billion lawsuit from the players union accusing NFL team owners of setting a secret salary cap in 2010 was kept alive by a federal appeals court Friday as the sniping between the two sides persists long after the end of the lockout. The 8th U.S. Circuit Court of Appeals in St. Louis partially reversed a federal judge's order that had rejected the union's collusion claim, sending the case back to U.S. District Judge David Doty for further proceedings. The three-judge appeals court panel that heard oral arguments in January disagreed with Doty on one of the union's two arguments for pursuing damages despite the 2011 collective bargaining agreement that was supposed to relinquish the union's right to sue for alleged breaches of the old CBA. The NFL called the appeals court decision "entirely procedural in nature" and said it's "far from validating" the claims of the NFL Players Association.