The Chinese currency renminbi, or yuan, retreated 37basis points to 6.1557 against the U.S. dollar on Friday, according to the ChinaForeign Exchange Trading System.In China's foreign exchange spot market, the yuan is allowed to rise or fall by 2percent from the central parity rate each trading day.The central parity rate of the yuan against the U.S. dollar is based on a weightedaverage of prices offered by market makers before the opening of the interbank market each business day.