Part 3 of the standard applies to direct acting indicating wattmeters and varmeters having an analogue display. NOTE For multifunction instruments, see Part 7. It also applies to: " Non-interchangeable accessories (as defined in Subclause 3.1.23 of IEC 60051-1:2016) used with wattmeters and varmeters. " Combination of the instruments and the accessories provided that the adjustments have been made for the combination; " Direct acting indicating electrical measuring instrument whose scale marks do not correspond directly to its electrical input quantity, provided that the relationship between them is known; " Instruments and accessories having electronic devices in their measuring and/or auxiliary circuits. This standard does not apply to: " Special purpose instruments which are covered by their own IEC standards; " Special purpose devices which are covered by their own IEC standards when they are used as accessories.