An electronic display device that allows the hierarchy or system to which
the display screen belongs to be easily identified, without narrowing the
display area of a plurality of screens constituting a director structure.
In the display device, a plurality of key input screens form a director
structure in association with each other. The directory structure includes
first to fourth hierarchy levels. Respective key input screens are located
at any of the hierarchy. Upon depression of a transition key in a basic
screen belonging to the first hierarchy, the display screen is switched to
one of key input screens belonging to the second hierarchy. The display
device changes the display color according to the hierarchy to which the
key input screen belongs in providing a display of a key input screen.
