 we wants to preserve consistent
state of the database by keeping cloned object unchanged.
If we deallocate memory immediately after cloning, new object can be
allocated at the place of cloned object and we loose
consistency. As far as memory deallocation is done in DyBASE by bitmap
using the same transaction mechanism as for normal database objects,
deallocation of object space will require clearing some bits in bitmap page,
which also should be cloned before modification. Cloning bitmap page will
require 