A certificate of occupancy, the document by which a state grants a right of occupancy over a piece of land under the Land Use Act 1978. Since the Act vested all land in each state’s Governor, a C of O is as close to owning land as anyone in Nigeria gets - in practice a long lease from the state.
Selling land that has a C of O needs the [[Governor’s consent]] as well. Without it, the transfer is invalid.