It is said that new currency 'yen' was determined according to the currency standard that 1 ryo (2 coins) of Manei nibukin = 1ryo (2 coins) of Meiji nibukin = (new currency unit) 1 yen gold coin.
ちなみに万延二分金一両分（2枚）＝明治二分金一両分（2枚）＝（新通貨単位）一円金貨という、貨幣基準で新貨幣単位「円(通貨)」が定められたといわれている。