The control of ULDs (containers) in an airline has important cost, commercial, and operational implications. To produce maximum efficiency in all these areas, control should therefore be exercised at a management level. Customers need containers of the right type, in the right place, at the right time,- and that means ULDs must be under control. The efficient circulation of equipment depends on an effective in-house control system, on an industry (IATA) identification code and ULD markings, and on an interline control. The interline control is provided by the IATA ULD Control Centre and this will expand as more airlines operate wide-body containerised aircraft.