Postal Explorer >
Publication 52 - Hazardous, Restricted, and Perishable Mail >
2 General Guidelines > 22 Marking Requirements > 226 Package Orientation Markings
Outer packaging that contains a primary receptacle (and secondary packaging, when required) of a liquid or other spillable material must be packed with the closure of the primary receptacle positioned upward.
The outer packaging must be plainly and legibly marked on two opposite sides with a package orientation marking consisting of two underlined arrows that point in the correct upright position.
Optionally, the two arrows may be enclosed in a rectangle. Specifications for package orientation markings are in 49 CFR 172.312. See Exhibit 226 for examples.
Package Orientation Markings
Note: Either design is acceptable.