un updated and displyed field in /dbm/vm

Hi

when we enter in to vehicle master /dbm/vm, we use to get a data tabs on LH side.

there is a TAB called VEHICLE GENRAL DATA in that ....there are 3 field entries

techinical field name - functional names as under

PDDATU-  production date

PSDATU- planned dely date

CDDATE- Confirm delivery date

i want to use those fields how can i get it activated ? these are under display mode though we select VEHICLE EDIT function( action QMOD).

Kaustubh