Due to an editing error, a condition agreed to by the orchestra of the New York City Opera in its compromise decision to end its strike was incorrectly stated in yesterday's Style section. The orchestra will lose a significant number of once-guaranteed work weeks.

The orchestra of the New York City Opera voted today to end its seven-week strike and to accept a compromise contract that includes a significant reinstatement of once-guaranteed workweeks.

The musicians ratified the proposal by a vote of 32 to 21.

The opera company announced it would resume its season at Lincoln Center on Sept. 21 with a new production of Massenet's "Cendrillon." City Opera's summer season originally had been scheduled to open July 7. Rehearsals for the musicians are scheduled to begin next week.

Industry executives today suggested--based upon incomplete details of the settlement--that the union had made several compromises in the face of the opera's threat to cancel its entire 19-week season.

The dispute was the first major confrontation between the newly elected leadership of New York Local 802 of the American Federation of Musicians and the management of a powerful performing arts organization.

"The musicians will never recoup the losses they suffered" during the strike, union president John Glasel said. What gains were made, he said, "were paid for dearly . . ."

The opera company's chief negotiator, board member and lawyer Martin J. Oppenheimer, said the contract was fair to both sides and "we're delighted . . ."

Under the terms of the settlement, the musicians will receive pay increases of 6 1/2 percent per year over the three-year life of the new contract; will take a reduction of one performance every other week in 1985, the last year of the pact; and will have fewer of their former guaranteed workweeks withdrawn than the opera company had originally demanded.

As recently as the 1981-82 season, the orchestra was guaranteed full salary, or vacation allowance, or supplementary unemployment benefits for a total of 36 weeks per year, orchestra spokesmen said. This season, the opera company unilaterally reduced that guarantee to 23 weeks.

The reduction, the key issue in the strike, was caused in part by the opera's decision to permanently cancel its spring New York season, by the cancellation of its annual visits to Wolf Trap Farm Park and to Los Angeles, and by the opera company's general financial distress.

Under a complicated formula, the settlement will increase the musicians' guaranteed workweeks to a total of at least 29 in 1985. Six of those weeks could be paid at half salary if the opera company is unable to offer performances.