War Orphans Tax - Compulsory surtax applied by the Turkish Empire in Word War I. From July 1915, all mail had to be franked with additional charity stamps for war orphans. Postcards and letters were surtaxed with 10 Para, registered letters and cards with 20 Para, and regular postage stamps were used. Foreign merchants in the Ottoman Empire lodged a complaint with UPU against this measure. In consequence, foreign mail was excluded from this surtax, but the normal postage rate was raised instead.

War stamp - A stamp issued during wartime to raise revenue for the war, and inscribed or overprinted as such. The stamp was applied in addition to the regular postage.

Watermark - A pattern or design within the substance of the paper which is impressed in the wet paper pulp during the manufacturing process. Some stamps are printed on watermarked paper to prevent counterfeiting, to identify the paper manufacturer, or to identify different stamps or postal stationery.

Wrapper - A form of postal stationery which pays the cost of the delivery of a newspaper or a periodical. The wrapper is a sheet of paper large enough to wrap around a folded or rolled newspaper, and with an imprinted stamp to pay the cost of postage.