Shipping containers have serial numbers that function as identifying marks. These numbers help shippers and freight forwarders track containers as they move through the shipping process.
The identifying mark will look like this: ICOJ 201067 
- The first three letters are the owner’s code, which is an abbreviation for the name of the owner of the container. It is registered with the ICB (International Container Bureau).
- The fourth letter is the product code. It may be the letter U, J or Z. U stands for all freight containers, J for detachable freight container equipment and Z for trailers and chassis.
- The next 6 digits are the registration number. This number is assigned by the owner operator to each container in their fleet.
- The last single digit highlighted in the box is the check digit. This is a control number used to verify the owner, product code and serial number.
There will also be an identifying code for the type of container, the tare weight (which is the weight of the empty container), the gross weight and the maximum payload.