Pressing shortly on one of the Arrow buttons (1.) will move an active cursor from
“soft key” to “soft key” around the frame. An active “soft key” is indicated by
inverse appearance. By pressing the Enter button (2.) a function behind a “soft key”
is selected and a selectable menu appears. Within such a menu again the navigation
is done via the Arrow buttons and the selections are made with the Enter button.
The red Escape button (3.) is for canceling any procedure and for closing open
menu windows in order to return to the measurement mode.