 Originally it was envisaged that the E-road network would be a motorway system comparable to the US Interstate Highway System.The declaration was amended several times before November 15, 1975, when it was replaced by the European Agreement on Main International Traffic Arteries or "AGR", which set up a route numbering system and improved standards for roads in the list.The AGR last went through a major change in 1992 and in 2001 was extended into Central Asia to include the Caucasus nations.