Hong Kong has three main systems of units of measurement in current use: * The Chinese units of measurement of the Qing Empire (no longer in widespread use in mainland China); * British Imperial units; and * The metric System. In 1976 the Hong Kong Government started the conversion to the metric system, and as of 2012 measurements for government purposes, such as road signs, are almost always in metric units. However, all three systems are officially permitted for trade, and in the wider society a mixture of all three systems prevails.