60 Part 2 · Entertainment Discipline Overview The basic function of lighting is illumination, of course, but it can also provide stunning effects, help to set a scene, or focus and direct the audience's attention. Light without control isn't much use for most shows, and because of this, control has long been a critical part of lighting design and system functionality. Gaslights offered the first centrally controllable lumi- naires; they were dimmed using mechanical valves--less gas produced less light. Modern "conventional" lighting fixtures are, of course, powered by electricity and have their intensi- ties controlled by electronic, solid-state valves known as dimmers. And, of course, intensity is now only one part of the lighting control equation; color, angle, focus, video image, and many other parameters now are all part of the designer's palette. The modern lighting market was basically created by the availability of open control stan- dards. Few can now imagine a world where it's not easy, inexpensive, and convenient to con- nect virtually any control console to any manufacturer's dimmer, color scroller, video server, or a wide array of other devices. L IGHTING C ONTROL E QUIPMENT There are generally three parts to a modern lighting control system: a control "console," the control data distribution system, and the controlled devices, such as dimmers, color scrollers, and moving lights.