What is a UN number and how is it used in IATA DGR?

• A. A two-letter code that identifies the origin country
• B. A four-digit identifier that uniquely identifies dangerous goods; used to select the PSN, class, packing instruction, and labeling requirements
• C. The weight range of the package in kilograms
• D. The batch number assigned by the manufacturer

Answer: (B)

A UN number is a four-digit code assigned to dangerous goods to uniquely identify what substance or article is being shipped. In IATA DGR, this number is used to look up the exact requirements for that item: the proper shipping name, hazard class, packing instructions, and labeling and placarding requirements. The UN number cross-references to the Dangerous Goods List, ensuring consistent handling, packaging, and documentation across shippers and carriers. The other descriptions describe things like country of origin, package weight, or a batch identifier, which are not what the UN number represents.