Multilateral agreement redacted by the Economic and Social Council of the United Nations during its conference on Road Traffic in Vienna from October 7th to November 8th, 1968, with the aim of unifying international signs, symbols, and markings. This had the objective of facilitating the international circulation on public roads by land, as well as increasing the safety of such roads. The convention, which, as for August 2016, had been signed by 69 countries, Spain being one of them, establishes the criteria of classification, shape, color, size, and symbols, which are essential in vertical traffic signs, but also some dispositions on road markings and traffic lights.