An exchange can operate under one of four main types of exchange rate systems:

Fully fixed exchange rates

In a fixed exchange rate system, the government (or the central bankin acting on its behalf) intervenes in the currency market in order to keep the exchange rate close to a fixed target. It is committed to a single fixed exchange rate and does not allow major flucutations from this central rate.

Semi fixed exchange rates

Currency can move within a permitted range, but the exchange rate is the dominant target of exonomic policy-making. Interest rates are set to meet the target exchange rate.