The Marine-Schiffspost card was sold on German naval vessels for the exclusive use of naval personnel. Because of the large naval presence in Tsingtau, however, it was common for naval personnel to post the cards at the post office in Tsingtau. This created an unusual situation with MSP cards were canceled with non-MSP cancels.
Eventually in July 1898, the post office in Tsingtau began selling the postcards directly. To prevent civilian use of the cards, the occupation troops were required to write their name, rank, and unit on the reverse side in order to have the cards properly posted.
A plate flaw -- short foot on "P" on "Pf" -- can be found on some copies.