In principle, PvP settlement of a foreign exchange transaction via CLS could be carried out extremely easily: the two parties to the trade pay the currency they have sold into CLS; CLS settles the two sides of the foreign exchange transaction simultaneously and pays out the currency to participants they have bought. Since with this extremely secure mechanism the flow of funds of each transaction settled also has to be transferred individually, the participants would have to provide large amounts of expensive liquidity. If one takes into account not only the fact that a party carries out a large number of foreign exchange transactions a day in which it acts sometimes as the buyer and sometimes as the seller of the same currency but also the considerable volumes traded on the foreign exchange market, the advantages of a liquidity-saving mechanism are obvious.