Each expression defines its own handler option. The handler informs the QueueProcessor how the expression should be handled during animation extents.
There are two options:
OneWay: the animation is either animated "on" or "off", depending on its activation state. Once it reaches the min or max configured extent, it is removed from the queue and forgotten.
RoundTrip: the animation is animated fully "on", held for the configured duration, and then animated fully "off".