The Postal Service revises Publication 52, Hazardous, Restricted, and Perishable Mail (Pub 52) to incorporate new requirements, for mailers to use unique service type codes and extra service codes within the tracking barcodes and electronic data submission for package shipments containing hazardous materials (HAZMAT) or dangerous goods (DG). This rule standardizes the acceptance and handling of package shipments containing HAZMAT/DG by collecting electronic data to ensure these items are handled appropriately with regards to the category of HAMZAT/DG contained within the package and to create electronic manifests for the Postal Service's air carrier suppliers. The Postal Service also amends the Mailing Standards of the United States Postal Service Domestic Mail Manual(DMM) to alter refund eligibility of Priority Mail Express containing HAZMAT.