The International Convention on Load Lines (ICLL) is an IMO Convention that is applicable for all vessels engaged in international trade, with the following exceptions: ships of war; ships of less than 24 meters in length; pleasure yachts not engaged in trade; fishing vessels.

The ICLL defines the maximum allowed draught of the vessel, and how this is to be marked on the side of the vessel.

The International Load Line Certificate verifies that the vessels strength and stability have been approved for the draught corresponding to the freeboard mark given on the certificate and that the vessel at the maximum draught has a reserve buoyancy and bow height in compliance with the requirements of the ICLL.
The requirement for reserve buoyancy is to ensure that the vessel is not broken down by heavy seas, while the requirement for bow height is to limit the amount of green seas on the deck.