The demonetization of postage and revenue stamps is the process by which the stamps are rendered no longer valid. In general, stamp demonetization is a rare event, since any unused stamp is effectively equivalent to its face value, and there is no financial disadvantage if postal customers use old stamps on their mail. Demonetization chiefly occurs in connection with major upheavals in the postal system, such as a transfer from one country to another, or currency changes, such as decimalisation, or a change of government. The process of exchanging millions or billions of stamps in the public's hands, plus that of exchanging post office stock, is usually complicated and difficult, and offers much interest for students of postal history. There are typically two parts to the process; first, the exchange of unused stamps for new ones of equivalent value. This normally occurs at post offices, with patrons bringing in their old stamps. The second part is the handling of mail with stamps already on it. Uncancelled letters, such as those dropped in mailbox, will get a grace period, ending at roughly the same time as the exchange of old stamps. Cancelled letters already in the mailstream may be accepted for a longer period, since remote post offices may not yet have exchanged their stamps, and sometimes there may be delays within the postal system itself. Eurozone In the Eurozone, some countries have demonetized stamps denominated in the old currency while others have not. The countries where pre-euro stamps are still valid include Belgium, France, Italy and San Marino. Austria Austrian stamps denominated in schillings were demonetized on 1 July 2002. Finland Finnish stamps denominated in marks were demonetized at the end of 2011. France Most French Franc stamps are still valid for postage, within France, at a rate of 6.56 new French Francs = €1 for post-1960 stamps and at a multiplier rate of 100 for pre-1960 stamps. A few stamps have been demonetised. Germany German stamps denominated in Deutsche Marks were demonetized on 1 July 2002. All stamps issued since 9 November 2000 are valid for postage. Ireland Irish stamps denominated in pounds were demonetized on 31 December 2002. Stamps issued since 2 August 2000 are valid for postage. Italy Italian stamps denominated in Lire are valid, if issued after March 20th, 1967. All Italian stamps issued in Euro and Lire-Euro are valid for postage. Malta Malta adopted the