01	Non-electrical Energy Conversion	Techniques and devices for the conversion of one form of energy to a form of non- electrical energy, but which do not primarily involve energy storage; General studies of energy conversion. If the application of a technique or a device is known, see the group where the application is treated.
02	Electric Power Production and Distribution	Techniques and devices used in the generation and distribution of electric power which do not primarily use energy storage. Includes electric power generators, transformers, converters, circuit breakers and electrical power transmission lines. For electrochemical power sources, See 10/03, Electrochemical Energy Storage. For electric power production devices which primarily use non-electrochemical energy storage, See 10/04, Energy Storage. For nuclear power plants, See 18/05, Nuclear Power Plants and Fission Reactor Engineering. For onboard electrical power systems, see group where application is treated.
03	Electrochemical Energy Storage	Devices which use chemical processes to produce electricity, such as electric batteries and electrical fuel cells.
04	Energy Storage	Techniques and devices for the storage and subsequent use of energy. Includes inductive, compressed gas, pumped hydro, capacitor banks, flywheels and thermal energy storage. For electrical batteries and battery components, See 10/03, Electrochemical Energy Storage. For devices which produce electric power without energy storage, See 10/02, Electric Power Production and Distribution. For solar cells, See 10/02, Electric Power Production and Distribution.