Rank in Judo judo association. For a rank to be recognized, it must be registered with the national judo organization or the Kōdōkan. In Japan, the use of belt colors is related to the age of the student. Some clubs will only have black and white, others will include a brown belt for advanced kyū grades and at the elementary school level it is common to see a green belt for intermediate levels. In Europe the belt system is white, yellow, orange, green, blue, brown and black for both senior and junior practitioners. Judokas who have attained the 6th Dan may also use
Orange (colour) also widely worn by workers on highways and by cyclists to avoid being hit. A herbicide called Agent Orange was widely sprayed from aircraft by the Royal Air Force during the Malayan Emergency and the US Air Force during the Vietnam War to remove the forest and jungle cover beneath which enemy combatants were believed to be hiding, and to expose their supply routes. The chemical was not actually orange, but took its name from the colour of the steel drums in which it was stored. Agent Orange was toxic, and was later linked to birth defects and other health