An organization known as the National Motor Freight Traffic Association (NMFTA) publishes a list of freight class designations, codes, and subclasses for many commonly shipped commodities (https://classit.nmfta.org/). You must pay a subscription fee to view this list. For more information about freight classes for free on our freight classes pages.
The National Motor Freight and Traffic Association has 18 freight classes numbered 50 to 500. The lower the freight class, the lower the cost of transporting that freight.
No, not all commodities have freight subclasses, although many do.