 The pre-2001 licence plates (white letters on black background) can be used indefinitely, but since they are obsolete they have to be replaced in case of change of vehicle's ownership.In the pre-2001 model, there were not sufficient letters in the Polish alphabet for each of the old voivodeships to have a single letter.Only the standard latin alphabet were used (outside Q), the specific Polish characters with diacritics were excluded in order to make the plates fully internationally readable.