Signs identifying the hazard class of the cargo and placed on the outside of the vehicle are known as _________.

Placards are used to warn others of hazardous materials. Placards are signs put on the outside of a vehicle that identify the hazard class of the cargo. A placarded vehicle must have at least four identical placards. They are put on the front, rear and both sides of the vehicle.
Placards must be readable from all four directions. They are 10 3/4-inches square, square-on-point, in a diamond shape. Cargo tanks and other bulk packaging also display the ID number of their contents on placards, or orange panels or white square-on-point displays that are the same size as placards, and placed near the placards.