ZHENGZHOU, China: Previously, I discussed the extent to which a currency could freely circulate as being crucial in determining whether it can become a major currency regionally or even globally. Some currencies, such as the British pound and Swiss franc, although not issued by the world's major economies, have achieved significant levels of free circulation and thus might also be considered to have joined the ranks of major currencies. Others, like the euro and Japanese yen, backed by sizable economies and free circulation, are as such as well.A year and a half ago, the United Kingdom suddenl...