Grains such as wheat, rye, maize, rice, oats, seeds and their processed forms have been commonly transported by ships. Grains have a tendency to settle and shift within a ship's cargo compartments.
A compartment may be full when the cargo is loaded but, due to ship's vibration and other movements, the grain settles leaving space at the top of the cargo. This space allows cargo to move from side to side in conjunction with the rolling and pitching of the vessel.

Fig: Hold of a bulk carrier that is grain clean and ready to load
As the cargo shifts the vessel lists to one side. The International Grain Code was written at a time when grain was predominantly carried onboard general cargo vessels, employing methods including saucering, bundling and strapping. However, modern bulk carriers are designed and constructed taking the problems of carrying grain into consideration. The BLU Code refers to loading and discharging operations and develops an understanding of procedures.
SOLAS regulation VI/9.1 (Requirements for cargo ships carrying grain) provides that a cargo ship carrying grain must hold a Document of Authorization as required by the International Grain Code, and for the purposes of regulation 9, the requirements of the Code should be treated as mandatory. A ship without a Document of Authorization must not load grain until the master satisfies the flag State Administration, or the SOLAS Contracting Government of the port of loading on behalf of the Administration, that the ship will comply with the requirements of the International Grain Code in its proposed loaded condition (regulation 9.2).
The International Code for the Safe Carriage of Grain in Bulk is commonly called the International Grain Code was adopted by the IMO Maritime Safety Committee by resolution MSC.23(59). It applies to ships regardless of size, including those of less than 500gt, engaged in the carriage of grain in bulk, to which part C of chapter VI of the 1974 SOLAS Convention, as amended, applies (A 1.1).
Intact grain stability criteria - Typical bulk carrier