In professional theatre the Stage Manager's function is to facilitate. The stage manager provides a central point of communication and support for all of the creative departments (i.e.: lighting, sound, set design, properties, special effects design, etc.) as they all work together to realize the director's "vision" of the new show. During rehearsals the cast and crew are added to the process as the stage manager continues to refine his understanding of the what the director wants the show to become. Come opening night, the stage manager becomes 100% responsible for every aspect of the show. His job is to "maintain the artistic integrity of the performances" and to maintain the master prompt script for as long as the show runs. He "calls" the performance cues to all of the tech departments, is responsible for (and to) the actors, is in charge of replacement rehearsals in the cast (if that becomes necessary) and all understudy rehearsals. In fact, after opening, if the director wants to call a brush-up rehearsal or even assemble the cast to give notes on a performance, he will schedule it through the stage manager.