Ships need to built according to a set standards of design and construction. These standards are drafted by the "international association of classification societies (IACS).
Different classification societies can have their own rules over and above the rules set by IACS.
Now before a ship is classed, classification society checks all the parameters related to construction and design. Some of these may be mandatory, other will not be.
Based upon the design and construction, class assigns "notations" for the ship. Notations are in form of symbols and letters. Each symbol and/or letter defines a particular aspect of the ship's design and construction.
The class notations are mentioned in the "Certificate of class". Below is the section of class certificate of a ship.
Each of these letters, numbers and symbol has a meaning.
For example, "construction symbol" signifies if the ship was built under the guidance of class or not.
Tanker for chemicals and oil: This means that the ship is designed to carry chemicals and oil.
E0: This notation means that ship is designed for UMS operation.
ESP: This means that ship is enrolled for "enhanced survey program".
What is the significance of these notation to the seafarers ?
Ship staff need to make sure that all the elements of class notations are properly maintained.
For example if the ship is classed for UMS operation, ship must be operated in UMS mode.
If the ship has class notation "ESP", master must ensure that ESP file is on board and maintained.