SDR stands for Special Drawing Right.

It is a currency unit of the International Monetary Fund and is used worldwide as a method of determining value. It is based on a basketful of foreign currencies and therefore fluctuates in value on a continual basis in the same way as any currency does.

Liability for sea, air and European shipments are determined by the number of SDRs allocated to each mode of transport and the £ / SDR exchange rate at the time.