An item that accepts fixed voltages from test points in another component or set, and displays them in such a manner that deviation from a predetermined voltage value is readily apparent. the display is in terms of "good" and "bad" and is not in terms of voltage values. for items that display the same or similar information that is derived from a radio frequency signal input, see monitor, error voltage. for items that indicate voltage values in either scaler or digital form, see voltmeter. see also indicator (as modified).