In order for OPS to become widespread among various ports and ship-owners, the nature and arrangement of power connections must be standardized. Neither a port owner nor a ship-owner can justify investment in expensive equipment to enable a shore connection system without assurance that such a system will be functional across many countries with alternative electrical characteristics in terms of voltage, frequency and other aspects. Work on a common standard for OPS for ships at berth began early in 2005. Major players in this effort have included technology suppliers, governments, port authorities, ship-owners (particularly cruise line, tanker and container ship companies), classification societies and others.