Photo: Dr. Jean-Paul Rodrigue, 2012
- Owner code. Consisting of three capital letters that identifies the owner of the container. There is an international agency that issues owner codes so that no single code is assigned to more than one owner. In the above case the container belongs to the American company Textainer, the world's largest container leasing company with a fleet of 1.7 million units. The great majority of shipping and container leasing companies advertise their logo on the container, so the owner is commonly easy to identify.
- Product group code. Appears right after the owner code and consists of one capital letter, either U, J or Z; U refers to a container, J refers to equipment that can be attached to a container, such as a power unit and Z refers to a trailer or chassis used to carry a container. Therefore, each mobile intermodal equipment has its own identification code.
- Registration Number (or Serial Number). A sequence of 6 digits where each container belonging to an owner has a unique value. Therefore, each owner code can have up to 1 million containers.
- Check digit. This single digit is used to cross-verify if the identification sequence is accurate. By convention it is boxed to make sure it is separated and is standing out from the registration number. Since terminal gates handle a large amount of containers, there is always a risk that the identification sequence was not correctly inputted. The standard procedure involves the sequence to be remotely inputted by a video camera with the operator entering the sequence manually in the information system or increasingly that sequence being inputted automatically through optical character recognition software. A numerical operation is performed on the container identification sequence which results in a single digit number, which is then compared with the check digit. If they match, then the identification sequence is accurate (there is still a probability for error, but it is very low).
- Size and type code. A sequence of 4 letter or digits that commonly appear right under the container identification sequence. Its purpose is to provide information about the dimensions and the type of container; the first character is related to the length of the container while the second character is relative to its height. On the above photo, the first two numbers 45 indicate that the container is a 40 footer (4; commonly the length of the container) of 9 feet 6 inches in height (5; high cube). The remaining two elements of the sequence (G1) indicate that it is a general purpose container.