The use of census, property and armament requirements produced a division among Roman census classes (distinct from the usual plebeian/patrician divide) in which four standardized unit types (reflecting how much money the soldier could spend on his own arms and armor) comprised each legion (the velitas, hastati, principes and triarii). These units operated in the maniple system which had developed in the 320s BC as a replacement to the traditional 'Italic' phalanx. In this formation the units were split into distinctive lines based on age, experience and wealth: