This standard applies to power meters measuring power levels from 1w to lkw. This standard does not apply to wattmeters and audio power level meters used by electricians.
SJ 2936-1988 history
2013SJ/T 2936-2013 General specification of medium power meter
1988SJ 2936-1988 Specification for medium powers wattmeters
SJ 2936-1988 Specification for medium powers wattmeters was changed to SJ/T 2936-2013 General specification of medium power meter.