What heating and cooling system types are compatible with the TH8320U thermostat?

The TH8320U is compatible with gas, oil, or electric heat with air conditioning, heat only two-wire systems, warm air, hot water, high-efficiency furnaces, heat pumps, steam, gravity, heat only with fan, cool only, and 750 mV heating systems. It supports up to 3 Heat/2 Cool systems. (Page 1)