some theater heavyweights like Mr. Lane were not even nominated; instead, several Tony Awards were given for productions that were always intended to be short-timers on Broadway, given that many of their film-star performers had to move on to other commitments. According to Mark Shenton, "One of the biggest changes to the commercial theatrical landscape—on both sides of the Atlantic—over the past decade or so is that sightings of big star names turning out to do plays has [sic] gone up; but the runs they are prepared to commit to has gone down. Time was that a producer would require a minimum commitment from his star of six months, and perhaps a year; now, the 13-week run is the norm." The minimum size of the Broadway orchestra is governed by an agreement with the musicians' union (Local 802, American Federation of Musicians) and The Broadway League. For example, the agreement specifies the minimum size of the orchestra at the Minskoff Theatre to be 18, while at the Music Box Theatre it is 9. Runs Most Broadway shows are commercial productions intended to make a profit for the producers and investors ("backers" or "angels"), and therefore have open-ended runs (duration that the production plays), meaning that the length of their presentation is not set beforehand, but depends on critical response, word of mouth, and the effectiveness of the show's advertising, all of which determine ticket sales. Investing in a commercial production carries a varied degree of financial risk. Shows need not make a profit immediately; should they make their "nut" (weekly operating expenses), or lose money at a rate acceptable to the producers, they may continue to run in the expectation that, eventually, they will pay back their initial costs and become profitable. In some borderline situations, producers may ask that royalties be temporarily reduced or waived, or even that performers—with the permission of their unions—take reduced salaries, to prevent a show from closing. Theatre owners, who are not generally profit participants in most productions, may waive or reduce rents, or even lend money to a show to keep it running. Some Broadway shows are produced by non-commercial organizations as part of a regular subscription season—Lincoln Center Theatre, Roundabout Theatre Company, Manhattan Theatre Club, and Second Stage Theater are the four non-profit theatre companies that currently have permanent Broadway venues. Some other productions are produced on Broadway with "limited engagement runs"