ETC microVision FX User Manual page 143

Chapter 7 Reference 7 - 11
Light/Dark/Off
This switch allows you to select either Light or Dark chase and to turn
the chase on or off.
Light
Setting switch to Light turns chase on with the channels that constitute
the chase step flashing on, then turning off when the next step begins.
Dark
Setting switch to Dark turns chase on with channels that constitute the
chase step flashing off, then turning on again when the next step
begins.
Off
Setting the switch to Off turns off the chase.