(1) AC or DC- Generally speaking alternating current or direct current shall be the first factor. (2) We also have DC meter when you need to measure the Direct Current. 2.About Function (1) As the content is limited, all functions mentioned above are the main functions (2) Other functions such as TOU, load control, friendly hours,RTC, plz refer to the technical specification or contact with our sales team. 3.About Application (1) The applications only for examples, for the pratical situation the energy meter can also be used for other applications. (2) Welcome to inquiry if you are not sure about the functions or application, we have free technical support