When I need to just enter country only I'll use dcountry1.dbf. dstate1.dbf when I'll need only to enter state in respect of country.

Actually, I am preparing an address book where user could store data as per his choice. If the user does not need district will not use ddistrict1.dbf. Others who need district will make entry in the ddistrict1.dbf

All the three .dbfs to be used in separate combo of related fields in the address entry form.

regards.