Changes of Denomination
Sometimes a stamp may have its denomination changed by the post office due to local circumstances. For instance, stocks of one value may be overprinted to show a different value due to stock shortages. In cases of hyper-inflation stamps have had their denomination changed by overprinting as existing denominations became worthless. In other cases, changes to the local currency have led to changes in denomination. For instance, when the Ryukyu Islands (at the time a United States protectorate) changed its currency from Yen to Dollars, a number of airmail stamps originally printed with Yen values were overprinted and re-denominated to cents in 1959–1960.
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