Red and black interpostal accountancy marks

The volume of interpostal mail increased by several thousand percent during the 19th century. Countries with bilateral revenue sharing agreements, including the Australian colonies, used four types of Accountancy Mark systems from 1843 to 1876. Marks on interpostal mail showed the amount of shared revenue between two or more postal entities. Accountancy Marks were shorthand notations for journal entry instructions to record amounts owing to, or amounts owing from other postal authorities. For prepaid mail, the calculation of shared revenues to be paid to the destination country was marked in red on outgoing mails, and for unpaid mail, the amount owed to the sender country for its share of unpaid mail was marked in black. Red was used to indicate a credit entry in the sending country account, and black was used to indicate a debit entry for an amount owed to the sending country. During the 33-year period, the system was changed from the recording of a simple manuscript or handstamp numeral marking, to PD, PP, and P abbreviation handstamps. The system was then modified to include Articles handstamps and Letter or Way Bills. Finally, a system of country-designated handstamps was used with specific amounts due. The paper supplies illustrations of how Accountancy Mark calculations were performed, and discusses the cost and time disadvantages and reliability issues of the Accountancy Mark system together with linkages to accounting.