The National Motor Freight Traffic Association (NMFTA) created the National Motor Freight Classification (NMFC). It is used for all interstate, intrastate, and foreign commercial movement of LTL cargo. NMFC codes provide standardized freight classes to determine the transportability of the large variety of commodities that are shipped together in LTL shipments every year.

Adding NMFC code to a shipment is technically optional, but the NMFC codes can help avoid reclassification and ensure you're using the correct freight class number.

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.