A displacement measuring instrument has a spindle penetrating a gauge body to be slidably supported relative to the gauge body to be displaced and a lifting lever manipulated from the outside for forcibly shifting the spindle. After recessing a top semiconductor layer and an underlying semiconductor substrate, a dielectric layer may be deposited and etched back to form embedded spacers. The platform assembly includes a platform frame to be connected to the vehicle, a nested, pivotally connected suspension frame to which the axle assembly is attached, and an actuator mechanism coupled at high mechanical advantage between the pivotally connected frames. A control unit is removably mounted to the tie plate. The selected graphic object is detected on the basis of the selection information. A visual representation of the markers and the position of the plow relative to the markers, is displayed on a screen associated with the monitor system.