definitions, location, and measurement of nationality and registration marks. The aircraft registration is made up of a prefix selected from the country's callsign prefix allocated by the International Telecommunication Union (ITU) (making the registration a quick way of determining the country of origin) and the registration suffix. Depending on the country of registration, this suffix is a numeric or alphanumeric code, and consists of one to five characters. A supplement to Annex 7 provides an updated list of approved nationality and common marks used by various countries. Country-specific usage While the Chicago convention sets out the country-specific prefixes used in registration marks, and makes provision for the ways they are used in international civil aviation and displayed on aircraft, individual countries also make further provision for their formats and the use of registration marks for intranational flight. When painted on the aircraft's fuselage, the prefix and suffix are usually separated by a dash (for example, YR-BMA). When entered in a flight plan, the dash is omitted (for example, YRBMA). In some countries that use a number suffix rather than letters, like the United States (N), South Korea (HL), and Japan (JA), the prefix and suffix are connected without a dash. Aircraft flying privately usually use their registration as their radio callsign, but many aircraft flying in commercial operations (especially charter, cargo, and airlines) use the ICAO airline designator or a company callsign. Some countries will permit an aircraft that will not be flown into the airspace of another country to display the registration with the country prefix omitted - for example, gliders registered in Australia commonly display only the three-letter unique mark, without the "VH-" national prefix. Some countries also operate a separate registry system, or use a separate group of unique marks, for gliders, ultralights, and/or other less-common types of aircraft. For example, Germany and Switzerland both use lettered suffixes (in the form D-xxxx and HB-xxx respectively) for most forms of flight-craft but numbers (D-nnnn and HB-nnn) for unpowered gliders. Many other nations register gliders in subgroups beginning with the letter G, such as Norway with LN-Gxx and New Zealand with ZK-Gxx. United States In the United States, the registration number is commonly referred to as an "N" number, because all aircraft registered there have a number starting with the letter N. An alphanumeric system is used because of the large numbers of aircraft registered in the United States.