Anti-radiation missile of radiation and explode when they got near it. SAM operators learned to turn their radar off when an ARM was fired at them, then turn it back on later, greatly reducing the missile's effectiveness. This led to the development of more advanced ARMs such as the AGM-78 Standard ARM and AGM-88 HARM missiles, which have inertial guidance systems (INS) built-in. This allows them to remember the radar's direction if it is turned off and continue to fly towards it. ARMs are less likely to hit the radar if the radar is turned off shortly after the missile is launched,
Direction, position, or indication sign sign category into direction signs, which are only those giving distances or directions to a given location; road identification signs (also known as "reassurance signs"), which repeat the name or number of the road, and place identification signs, which give the name of a landmark, such as a town, river or border. Unlike the other classes of sign, direction signs remain broadly undefined by the convention; the only restrictions given are that direction signs must be either a rectangle or an arrow shaped pentagon, and that they may not contain placenames in more than two languages. Additionally, direction signs on