However, in 1980, a more extensive system called ZIP+4 was introduced that contained an additional 4 numeric letters.
ເຖິງຢ່າງໃດກໍ່ຕາມ, ໃນປີ 1980, ລະບົບທີ່ກວ້າງຂວາງກວ່າທີ່ເອີ້ນວ່າ ZIP + 4 ໄດ້ຖືກ ນໍາ ສະ ເຫນີ.