Maritime containers that transit around the world have a standardized registration system for control purposes. Therefore, it is recommended that all maritime containers involved in international maritime cargo transportation be registered with the Bureau International du Container (BIC) and marked with a series of identification codes regulated by ISO 6346 and the subsequent update ISO 2716. This nomenclature provides information about the types and characteristics of maritime containers.

International Identification Code and Nomenclature for Containers

Each maritime container has an alphanumeric code (registration) divided into different sections or sub-codes, which provide information about the container’s owner and various characteristics. This registration consists of several sub-codes or sections:

Owner Code

An essential code in any maritime container consisting of four letters. The first three letters identify the owner of the container.

The fourth and final letter of the owner code associates the container with a group of containers in international transportation:

• U: For all containers compliant with ISO standards.
• J: For demountable containers.
• Z: For trailers and chassis.

The letter U is usually the most common among maritime containers used for international transportation.

Serial Number

Consists of 6 digits determined by the owner, a unique code different from the rest of the owner’s containers. The number is purely for identification purposes and does not provide additional information.

Check Digit

Usually located at one end of the container, immediately following the serial number. This digit helps verify if the owner code and serial number are correct using an algorithm set by the ISO standard.

Other Codes with Additional Container Information

Maritime containers are also marked with several numeric series that indicate the container’s dimensions and type in its country of origin.

Container Dimensions and Properties

Optional two-letter code with the abbreviation of the country. The code for the country of origin indicates the country where the container is registered, not the owner’s nationality.

In addition, maritime containers have other marks that indicate operational and safety data for transportation.

Mandatory Operational Marks

Each container must have a series of operational marks:

• Maximum Gross Weight (MGW): Maximum weight of the loaded container, indicated in both kilograms and pounds.
• Tare Weight (TARE): Weight of the empty container, in pounds and kilograms.

Optional Operational Marks

• Net Weight: The container’s cargo capacity, which is the difference between the gross weight and the tare weight.
• Internal Volume (CU.CAP): Internal capacity volume of the container, indicated in cubic meters and cubic feet.

Optional Marks or Signs

There are several optional marks or signs:

• Weight Warning: Yellow triangle with a black border, indicating that the container is extremely heavy.
• Height Warning: Yellow rectangle with black borders, displaying the container’s height for those containers exceeding the standard conventional height.
• Certificates and Seals: The containers have undergone various audits or seal controls for the security of the goods.
• Owner’s Logo: Usually placed on the sides or doors of the containers.

Additionally, reefer containers are required to display a sign indicating the risk of electrical hazard. A yellow triangle sign with a black lightning bolt.