other vehicle functions 36 include by way of example a seatbelt warning status 38 which status may be displayed on a mirror based display 40 preferably mirror based display 40 may be located on at or adjacent interior rearview mirror assembly 16 mirror based display 40 may be of various forms including that disclosed in commonly assigned u s patent application ser no 09 799 414 filed on mar 5 2001 by mccarthy et al entitled complete mirror based global positioning system gps navigation solution the disclosure of which is hereby incorporated herein by reference additionally display 40 may display magnetic vehicle heading information from a magnetic sensor 42 the information being supplied over network 34 additionally reverse gear status from a reverse gear sensor 44 may be supplied over network 34 to cause digital electrochromic mirror 18 to assume a high reflectance level when vehicle 11 is placed in reverse gear rearview mirror system 10 may additionally receive engine information 46 and or door opener information at 48 over network 34 and activate general lighting 50 located in at or on interior rearview mirror assembly 16 such as when a door of vehicle 11 is opened status from an alarm assembly 52 may also be conveyed over network 34 and displayed by display 40 dim ratios or partial reflectance levels developed from light sensors 24 can be transmitted over network 34 for.