Overprint on official stamps to transfer them into the category of regular postage stamps: "private" over the word "official", "0" over the "No." sign, a line covering the district (school) name and number, and a new denomination of 1 kopek. Print run: 6 copies.
Official stamps were intended for official correspondence carried by the zemstvo post. Used in 1912-1914, issued free of charge, but accounted for. Blue ones were for 10 medical districts.