I have never been a schedule coordinator, but I am familiar with the position. Indeed, it is usually found at large opera companies. The scheduler (aka rehearsal coordinator) keeps track of all the artist hours and rehearsal/performance space needs. When companies are so large, it is very possible that a singer might be asked to meet with the maestro, attend a costume fitting, and rehearse a scene all at once. So the schedule coordinator works to be sure this doesn't happen. Basically, every request requiring space use and/or artist time goes through this office (or at least that's the way it's supposed to work!). In addition, the SC keeps track of all the hours everyone is working - very important for tracking all the unions that might be working on the opera (AGMA, IATSE, AFofM). Principal artists can usually work no more than 6 hours per day - and that would include meetings/fittings. But that rule varies by company. And finally, the SC makes sure that rehearsal space is prepared for use - reserved, cleaned, temperature controlled, with a tuned/prepped piano, props and production tables if necessary, etc etc. Of course, the SC also communicates all this scheduling to everyone, everywhere. Though it sounds like a small-ish job, it is a mighty task! Schedulers usually work very closely with the stars, conductors, directors, and SMs. SCs need to be extremely diplomatic, but also very practical and pragmatic. SCs are creative in their own way - brilliantly tracking, solving, and preemptively avoiding dozens of conflicts each hour. (That's a quick summary of the job duties. If you want to know anything more specific, ask away!)