Black out function - Definition

Depending on the device, the Black-Out feature is simply that. A remote or other way of turning off the light source without having to kill power to the device. This is usually achieved by a solid gobo wheel pattern or clever electonics to turn off the globe.

ROQ out

depends on what type of controller and lights your dealing with...if your using a stage dimmer board then it would cut off power to each light but not shutting off the dimmer pack by shutting of all of the channels on the board... on a DMX controller it would tell the intel fixture to do as what ROQ said, that or close a shutter.
DJ Borris

As Roq stated most "blackout" effects as described by the fixtures and not the controllers are achieved by a shutter, while others achieve the effect by turning off the buld, and leaving the fixture running (ie, the mirror/motors/fans). Some effects blackouts are achieved by turning off the bulb, but it does depend on the fixture, and the bulb being used. You do not want to turn on and off a gas discharge bulb constantly, as it takes too long to warm up, and can cause damage o the bulb (ie. these use a shutter), but for lumens per watt, and cost effect on bulb life and power consumption, gas discharge are one of the best.

Thanks a bunch for the info guys. I appreciate it!