IEC 60523 Ed. 1.0 b:1975

Applicable to d.c. potentiometers assembled from resistors and switches and operating entirely on direct current, having accuracy classes of 0.0005 … 0.1, as well as to auxiliary equipment which is a built-in part of the potentiometer. Classification system. Permissible errors for each accuracy class. Conditions for determination of errors. Markings. Information by the manufacturer.