UN number
Dangerous goodsUnited Nations number
A four-digit code that identifies a specific dangerous substance or article.
In practice
For example UN1203 is petrol, UN3480 is lithium ion batteries, UN1263 is paint. Found in section 14 of the MSDS. The UN number decides the class, packing group, packing instructions, and whether the carrier accepts it.
Seen in the wild
UN3481, lithium ion batteries packed with equipment, Class 9, PI 966.