What is the main function of "Reverse gear" in Adapter Box G2 settings?

This is to prevent the heat pump from remaining working at the preset gear after Adapter Box G2 is disconnected from the inverter, which might cause extra usage of the grid power. When the connection method is DO or AO, the selectable range of the reverse gear is 0 to the maximum gear of the gear setting; when the connection method is SG ready, the selectable range is Signal OFF and Signal ON.