A primary category containing information pertaining to postal affairs such as controlled circulation of publications; rates and fees; penalty; franked and official mail; free mail for the blind; collections; deliveries; commemorative stamps and special services.


Subject categories and sub-categories fully available for research are bolded. Closed categories and sub-categories have a simple phrase describing their contents.


                                    DESCRIPTION OF SECONDARY FILE CODES


File Code                               Description


PO                                          Postal Service