UN38.3 refers to Chapter 38.3 Lithium Metal and Lithium-ion Batteries of the United Nations Recommendations on the Transport of Dangerous Goods -- Manual of Tests and Criteria, which sets out the procedures to be followed for the classification of lithium-metal and lithium-ion batteries during transport. Lithium batteries and equipment/vehicles with lithium batteries are generally required to pass the UN38.3 test first before transport.