The ERM is a program through which member countries of the European Economic Community agree to maintain parity in exchange rates among their currencies. Limits are set on the amounts by which exchange rates may vary between any two currencies. If an exchange rate reaches the limit, the central banks of the two countries intervene in the market to ensure that the limit is not exceeded. The ERM was established in 1979 with agreement by Belgium, France, West Germany, Luxembourg, the Netherlands, and Denmark to limit fluctuation in the bilateral exchange rates between their currencies to n2.25%. Italy, which was also a member, did not limit fluctuation to n25% until 1990. Spain joined in 1989, the UK in 1990, and Portugal in 1992, each agreeing to a wider band of 6% fluctuation in the bilateral exchange rates in the value of their currencies against other ERM members. Disruptions in September 1992 led to the withdrawal of Italy and the UK and to some parity realignments. The ERM has since resumed, with provisions allowing currency fluctuations of 15 percent.