Capital Flow Watch

A Special Drawing Right (SDR) is the monetary unit of the reserve assets of the International Monetary Fund (IMF). The unit was created in 1969 in support of the Bretton Woods system of fixed exchange rates to alleviate the shortage of U.S. dollar and gold reserves in the expansion of international trade.[1] The SDR unit is defined as a weighted sum of contributions of four major currencies, reevaluated and adjusted every five years, and computed daily in terms of equivalent United States dollars. Special Drawing Rights are not a currency, but they represent potential claims on the currencies of the IMF members. SDRs obtain their reserve asset power from the commitments of the IMF member states to hold and honor them for payment of balances. The IMF uses SDRs for its monetary unit of account. SDRs are denoted with the ISO 4217 currency code XDR.
Special Drawing Rights are allocated to member states as a low cost alternative to debt financing for building reserves. Such allocations provide an unconditional liquidity for the SDRs. As of September 2009, total SDR allocations amount to SDR 204 billion.
Special Drawing Rights carry an interest rate that is computed weekly by the IMF. It is paid or received quarterly by the members for deviations of their SDR holdings from their SDR allocations. (Wikipedia Feb 2010)