If a heat pump is commanded enabled in either heating or cooling
mode, it is removed from the staging order of the opposite mode
until it has been off for dtOff.
To avoid concurrent stage transitions between heating and cooling modes, "commanded enabled in a given mode" should be interpreted as "required to run in a given mode", and evaluated before the heat pump is actually enabled. Event sequencing during stage transitions introduces a delay between these two events. During this delay, the heat pump should not be considered available for the opposite mode.