| Shipment ReferencesWhat is this?The reference numbers that are identifying information for the
  shipment. These numbers will be sent to other railroads and
  returned to you on a freight invoice. When is it used?When the information is required to be sent in your shipping
  information. Information availableThe following information can be provided in this block: 
    
      | Information | Required | Notes |  
      | Shipment References | Optional | Customer references used to identify
      different informaton pertaining to the movement of the
      shipment. |  
      | Code | Optional | Numerical code relating to the reference selected. |  |