For the UN Symbol on UN Specification packages, there is a technical difficulty in embossing the UN symbol in a circle on metal packaging material. In place, as written in DGR 126.96.36.199.1 (a) in the last sentence, it is permitted to emboss the letters “U N” in capital letters on metal drums and the like.
In the Note immediately following 188.8.131.52, it says while handwritten UN specification Package markings continue to be unacceptable, instead of having the entire package symbol printed or embossed, it is now permitted to have some part say rubber stamped. In such a case, there is a need to prove to the airline that the package is authentic. It is therefore advisable for the shipper to have the driver take along a copy of the UN Package Test Certificate which the package manufacturer had provided when the UN package was purchased.
By presenting the Test Certificate on acceptance check, the shipper can prove that the package is authentic thus avoiding unnecessary confusion at time of acceptance. Some 4G boxes may have the letters UN printed horizontally instead of the circle symbol. If the Test Certificate matches the actual symbol on the package, the airline will acknowledge the package as authentic.