ME Layer Mode
The ME Layer Mode uses an ME configurable program output to create a composite alpha from the keyers on that ME that is then available to another ME as a single alpha source. This allows you to re-enter the background bus of an ME into the key bus of another ME as a single Auto Select key. The key video comes from the output of the source ME and the key alpha comes from the configurable program output that is set to Layer Mode for the source ME.
Tip: You must set up the auto key with the configurable program output as the alpha and whatever source you want as the fill.