National Motor Freight Classification (NMFC) is the freight classification system that was created by the National Motor Freight Traffic Association (NMFTA) and is used for all interstate, intrastate, and foreign commerce movement of LTL cargo. NMFC codes provide standardized freight classes to determine the transportability of most of the countless different commodities that are shipped together in LTL shipments each year.

NOI stands for Not Otherwise Indicated. This is used when a commodity does not have an NMFC code. In these cases, density is usually used to determine freight class.