DOT hazard code,

Definition of DOT hazard code:

1. US Department of Transport (DOT) classification of dangerous material 1: Explosive, 2.1: Flammable gas, 2.2: Non-flammable gas, 2.3: Poisonous gas, 3: Flammable liquid, 4.1: Combustible solid, 4.2: Spontaneously combustible, 4.3: Dangerous when wet, 5.1: Oxidizer, 5.2: Organic peroxide, 6.1: Poison (Keep Away From Food), 6.2: Infectious material, 7: Radioactive, 8: Corrosive, 9: Miscellaneous. Like the European ADR system, it too is based on the UN recommendations.