Optical and Audiable Signaling Devices
Stack Lights
Color Code - General Principles

	COLOR	USE
		safety application	process applications	state of the installation
	red	extreme danger	emergency	faulty
	yellow	beware/dangerous conditions imminent	not normal	not normal
	amber	beware/dangerous conditions imminent	not normal	not normal
	green	normal conditions	normal	normal
	blue	defined action
	white clear	no particular meaing
	black