欧州為替相場メカニズム
The creation of a European single currency became an official objective of the European Economic Community in 1969. In 1992, having negotiated the structure and procedures of a currency union, the member states signed the Maastricht Treaty and were legally bound to fulfil the agreed-on rules including the convergence criteria if they wanted to join the monetary union. The states wanting to participate had first to join the European Exchange Rate Mechanism.