PG
Dangerous goodsPacking Group
A rating of how dangerous a substance is within its class: I is high danger, II medium, III low.
In practice
The packing group sets how strong the packaging must be (X, Y, or Z rated) and the quantity limits. Shown in section 14 of the MSDS and on the DGD. Not all classes use packing groups; gases and Class 9 batteries do not.
Seen in the wild
UN1263 Paint, Class 3, PG III.