UN Recommendations on the Transport of Dangerous Goods

The UN Recommendations on the Transport of Dangerous Goods are contained in the UN Model Regulations prepared by the Subcommittee of Experts on the Transport of Dangerous Goods of the United Nations Economic and Social Council (ECOSOC). They cover the transport of dangerous goods by all modes of transport except by bulk tanker. They are not obligatory or legally binding on individual countries, but have gained a wide degree of international acceptance: they form the basis of several international agreements and many national laws.
"Dangerous goods" (also known as "hazardous materials" or "HAZMAT" in the United States) may be a pure chemical substance (for example, trinitrotoluene (TNT), nitroglycerin), mixtures (for example, dynamite, gunpowder) or manufactured articles (for example, ammunition, fireworks). The transport hazards that they pose are grouped into nine classes, which may be subdivided into divisions and/or packing groups. The most common dangerous goods are assigned a UN number, a four digit code which identifies it internationally: less common substances are transported under generic codes such as "UN1993: flammable liquid, not otherwise specified".
The "UN Recommendations" do not cover the manufacture, use or disposal of dangerous goods.
History and principles.
The first version of the "Recommendations on the Transport of Dangerous Goods" was produced by the ECOSOC in 1956. From 1996, the "Recommendations" were effectively split into two parts: the "Model Regulations", which form a suggested drafting for laws and regulations on the transport of dangerous goods; and the "Manual of Tests and Criteria", which contains technical information about methods of testing products to ascertain their hazards. The 21st edition of the "Recommendations" was published in 2019.
The container requirements include some material and construction requirements but also performance testing is required. The package testing is based on the packing group (hazard level) of the contents, the quantity of material, and the type of container.
The UN recommendations are implemented by regulatory bodies in each country: Transport Canada, United States Department of Transportation, etc. Some carriers have additional requirements.