3 Labelling3.1 Labelling of the control equipmenta. Valves, motors, position switches, etc., must be labelled permanently and in compliance with the technical documentation. The labelling must be assigned clearly and distinctively to the device.b. If connections of pluggable devices (e.g. valves, pumps, signal encoders) present the risk of being confused with each other, the cable must be labelled in addition to the fixed labelling.c. Labels are to be designed to be permanent and to be resistant to heat, oil, light, chemical influences, etc.d. In systems with aggressive media, resistant materials (e.g. plastic with plastic grooved pins) and in the heat area, metallic materials (e.g. aluminium) must be used.3.2 Labelling within control cabinetsItem designation as specified by DIN EN 61346-2Permanently on or next to the device