A.
The Japanese equivalent of a “Cylinder” comes from a Japanized German term, “Bombe”. It is not a steel drum (1A1). Specification and details are written in DGR 6.4 covering 16 pages. Cylinders are not solely used for gaseous substances. When permitted in the Packing Instructions, cylinders can be used to pack liquids, powder or solid substances. Details are written in DGR 5.0.6.6 from 5.0.6.6.1 through 5.0.6.6.9.
You appear to be mixing up the definition and the codes. We will help you untangle the mix-up. Please refer to the following explanation.

1. UN Specification 1A1 packaging is a “Non-Removable Head Steel Drum” and it is not any of the drums. Please refer to DGR Table 5.0.C and DGR 6.2.1.


2. UN Specification Cylinders are marked as illustrated in DGR Table 6.4.A. There is no 1A1 code shown. Detailed specification is written in DGR 6.4 covering 16 pages. .


3. DOT packagings used in U.S. as well as Cylinders approved by Japanese High Pressure Code can be used provided they satisfy DGR 6.4.3 Requirements for Non-UN Cylinders and Non-UN Closed Cryogenic Rceptacles. However, they must not carry UN package marking..


4. If the Packing Instructions show “Cylinder as permitted in 5.0.6.6” in the “single packaging” box, Cylinder may be used for liquids and solids. As examples, please refer to PI 354 (used for liquid substances) and PI 448 (used for solid substances) where the use of Cylinders are permitted..

As aforesaid, I hope we were able to clear your mind and the definition of Cylinder and 1A1 Steel Drum is now clear to you..