Iingcango zomlilo ezinezixhobo ezahlukeneyo kunye nemisebenzi inamaxabiso ahlukeneyo, kuxhomekeke kwiimfuno. Umsebenzi obaluleke kakhulu weengcango zomlilo ngumlilo kunye nokusebenza kokushisa ukushisa, okwahlulahlulwe kwiintlobo ezintathu: A, B, kunye noC. Wamkelekile ukuba uqhagamshelane nathi.