In theater a rail refers to a long metal pole suspended above the stage (and sometimes above the audience) from which lighting fixtures and curtains may be hung. Usually these rails can be raised or lowered via a fly system , both for ease of use and to have curtains and other items suspended from the rails appear to "fly in" during a performance. Some theaters have chosen to do away with this system in favor of a static network of rails accessable only from catwalks above the stage. This is a safer approach, in that there is less chance of rails accidentally falling, but makes it much more difficult to access the rails and reqires a lot of space for the construction of the catwalks.