This part of the Chinese metering series covers static meters for active energy in the high accuracy classes used for the settlement of energy transferred between network operators and for large industrial consumers, and it is one of the documents on which the centralised verification of meters in China is based. The class designation carries a specific meaning in the technical requirements: meters of this accuracy must remain within their error limits at very small currents as well as at rated current, and must do so over a wide range of power factor and temperature, which places demands on the current sensing and the conversion circuitry that ordinary consumer meters do not face. The standard also governs the registers and the interfaces by which the meter is read, an area where Chinese practice has moved faster than most other markets because of the early introduction of remote reading. It is applied together with the accuracy part that defines the error limits themselves.