GE PAC 4020 System Manual page 41

The functional lights may be individually lighted
according to the function selected on the function
switch, or a single light behind all demand functions
may be used. In either case, the demand functions
lights are available in a wide range of color codes
so that all summary functions can be one color,
all limit functions another color, etc.
Also, audible alarms, (bells, buzzer, etc.)
can be incorporated which sound with the activation
of special alarm lights.
38
In some applications, a key- switch is desir-
able in place of the memory change pushbutton, to
prohibit unauthorized changes. Such a key-switch
may be substituted without changing the design or
function of the console.
Special Operator's Consoles
Special operator consoles are provided where
the standard consoles do not meet the requirements
of the process control application.