In some other countries, monetary policy is anchored to a fixed or stable exchange rate formula, instead of to the money supply. This is perhaps good for countries with a relatively open economy (such as South Africa is now becoming).
It is a precondition for the successful implementation of this type of model that the country will be able to stabilise the exchange rate through regular intervention in the foreign exchange market. To begin with, the central bank must have access to a substantial amount of foreign reserves to enable it to intervene in the market for foreign exchange in a meaningful way.