EVS-EN 60523:2001

This standard applies to d.c. potentiometers assembled from resistors and switches and operating entirely on direct current, having accuracy classes of 0.0005 ... 0.1 (5 ppM ... 1000 ppM parts per million). Is applies also to auxiliary equipment which is a built-in part of the potentiometer.  This standard does not apply to potentiometers which are set automatically or semi-automatically nor to those which also employ graduations on the null detector to obtain a part of the indicated value, nor to external auxiliary equipment used with the potentiometer.