ECO Mode, what does it do?

The user manual supplied with the unit is pretty brief if not pitiful. What is ECO mode and what does it do? Thanks

ECO Mode automatically shuts off the AC inverter after 4 hours of low or no load. It’s a nice feature for when you forget to turn off the AC so that you don’t loose overhead power from the inverter just being on. ECO Mode does not effect the DC, and DC will stay on. ECO Mode also does not shut the entire sogen off. It only shuts off the AC.