the Commonwealth Countries formerly part of the British Empire are likely to retain a modified version of the British laws including the basic principles regarding road safety. Usage of color in Hong Kong Hong Kong's raised marker colors are identical to those used in the United Kingdom. White — For lane markings and central reservation (US: median) on motorways and dual carriageways Red, yellow or amber — Lines that should not be crossed. Red is used for the left side of a dual carriageway, while yellow or amber is used for the right side of a dual carriageway. Green — A line that may be crossed, such as a slip road or lay-by Usage of color in Australia While Australian designs generally follow those in the US, the colors generally follow European usage. Differences from European usage include: Blue — Usually used to mark the location of fire hydrants, as in North America Yellow — In addition to marking the median of freeways, in Victoria single yellow reflectors are used with broken yellow lines to denote tram tracks on which motorized traffic can drive, and double yellow reflectors are used with solid yellow lines to denote tram tracks on which motorized traffic may not drive other than to cross. Usage of color in Latin America For countries in Latin America, the colors of raised markers vary by country to country. For most countries, they tend to generally follow the European counterparts rather than North American counterparts, but in several countries of Latin America, such as Mexico, the usage of blue follows the North American counterpart. History Cat's eyes made out of metal were the earliest form of retroreflective pavement markers, and are in use in the United Kingdom and other parts of the world. They were invented in the United Kingdom in 1933 by Percy Shaw and patented in 1934 (UK patents 436,290 and 457,536), and the United States in 1939 (US patent 2,146,359). On March 15, 1935, Shaw founded Reflecting Roadstuds Ltd, which became the first manufacturer of raised pavement markers. The plastic markers now used widely throughout the United States and elsewhere did not appear until more than two decades later. They were originally invented by American engineer Sidney A. Heenan in the course of his employment with the Stimsonite Corporation in Niles, Illinois. Heenan filed an application for a patent on October 23, 1964. Patent No. 3,332,327