The rating, tare mass and payload of a container is marked on its wall, usually on the end (rear) door in the case of an end-loading dry cargo container.
Each container has an identification code or container number---a combination of the 4-letter characters that identify the owner (the operator of container) and the 7-numeric characters that identify the container. The container number can be found on the outer and inner side walls.
The container number is entered on the bill of lading to facilitate the identification and tracking of the container and the cargo.