The ultimatum issued by the N.B.A. to its players over the weekend not only threatens them with a worse labor deal, but also a massive pay cut if they do not make a deal by Wednesday afternoon.

A letter sent by David Stern, the commissioner of the N.B.A., to the players union Sunday contrasts the proposal on the table — highlighted by a 50-50 split of revenues — with a “reset” proposal that would cut the players’ share to 47 percent, roll back current contracts, impose a hard salary cap and reduce contract lengths.

The salary rollback, which was part of the N.B.A.’s first controversial proposal in 2010, had not been included in any league proposal since the weekend of Oct. 1, and it was not publicly mentioned by Stern when he announced the ultimatum early Sunday morning.

But the rollback was included in the letter Stern sent to Billy Hunter, the union’s executive director. A copy of the letter was obtained by The New York Times.