in an offshore jurisdiction where they are leased or purchased but financed by banks in major onshore financial centres. The financing institution may be reluctant to allow the aircraft to be registered in the carrier's home country (either because it does not have sufficient regulation governing civil aviation, or because it feels the courts in that country would not cooperate fully if it needed to enforce any security interest over the aircraft), and the carrier is reluctant to have the aircraft registered in the financier's jurisdiction (often the United States or the United Kingdom) either because of personal or political reasons, or because they fear spurious lawsuits and potential arrest of the aircraft. International standards The first use of aircraft registrations was based on the radio callsigns allocated at the London International Radiotelegraphic Conference in 1913. The format was a single letter prefix followed by four other letters (like A-BCDE). The major nations operating aircraft were allocated a single letter prefix. Smaller countries had to share a single letter prefix, but were allocated exclusive use of the first letter of the suffix. This was modified by agreement by the International Bureau at Berne and published on April 23, 1913. Although initial allocations were not specifically for aircraft but for any radio user, the International Air Navigation Convention held in Paris in 1919 (Paris Convention of 1919) made allocations specifically for aircraft registrations, based on the 1913 callsign list. The agreement stipulated that the nationality marks were to be followed by a hyphen then a group of four letters that must include a vowel (and for the convention Y was considered to be a vowel). This system operated until the adoption of the revised system in 1928. The International Radiotelegraph Convention at Washington in 1927 revised the list of markings. These were adopted from 1928 and are the basis of the currently used registrations. The markings have been amended and added to over the years, and the allocations and standards have since 1947 been managed by the International Civil Aviation Organization (ICAO). Article 20 of the Convention on International Civil Aviation (Chicago Convention), signed in 1944, requires that all aircraft engaged in international air navigation bears its appropriate nationality and registration marks. Upon the completion of the necessary procedures, the aircraft receives its unique "registration", which must be displayed prominently on the aircraft. Annex 7 to the Chicago Convention describes the