CAN CSA Z431-12:2016 pdf download.Basic and safety principles for man-machine interface, marking and identification一Coding principles for indicators and actuators
5.2 Actuation modes
Actuating devices may be used in the following modes for giving manual commands:
a) Alerting
To alert the personnel to certain conditions, for example, danger.
b) Influencing
To operate the equipment or to influence processes by manually given commands.
c) Confirmation
To acknowledge an alarm or a certain given information.
NOTE For example, when a flashing annunciator is acknowledged it becomes steady.The meanings of actuation codes shall be as given in table 9.
5.2.1 Non-illuminated actuators
5.2.1.1 Emergency actuators
EMERGENCY-STOP / OFF actuators shall be identified by the colour RED (see table 9). Exceptions are allowed, if colour is not available ， in which case other means shall be employed to reliably identify the function of the actuator. If the same actuator is used for both emergency and normal STOP / OFF operation the colour shall be RED. Exceptions are allowed, if colour is not available.
5.2.1.2 STOP 1 OFF actuators
WHITE, GREY and BLACK are the preferred colours for STOP / OFF actuators, with the main preference being for BL ACK. RED is also permitted. GREEN shall not be used.
5.2.1.3 START / ON actuators
WHITE，GREY and BL ACK are the preferred colours for START / ON actuators, which cause the closing of switching devices and the equipment to start, with the main preference being for WHITE. GREEN is also permitted. RED shall not be used.
5.2.1.4 Use of WHITE and BLACK for specific meanings
Where the colours WHITE and BLACK are used to distinguish between START / ON and STOP / OFF actuators, then the colour WHITE shall be used for START / ON actuators and the colour BLACK shall be used for STOP / OFF actuators.
5.2.1.5 The same actuators serving for START and STOP or ON and OFF
5.2.1.5.1 WHITE, GREY and BLACK are the preferred colours for actuators which, when actuated several times, act alternately as a START / ON and STOP / OFF actuator. The colours YELLOW and GREEN shall not be used. The colour RED shall be used only in cases where the same actuator, other than a push-button, is used for both EME RGENCY-STOP / OFF and normal operation.
5.2.2.1 Types
Distinction is made between the types of illuminated actuators according to the colour displayed by the illuminated part of the actuator.
Type a Actuators which have the same colour whether or not they are lit.
Type b Actuators which have a single colour when lit that is different from the colour when not lit and both colours have meanings.
Type C Actuators which have more than one possible colour of lighting, for example, to indicate different conditions, but the colour when not lit is without meaning.
NOTE Lamps which are used as signal lights, but which are designed to be pushed for testing the lamp, are not considered as illuminated actuators.CAN CSA Z431-12 pdf download.