Britain's 1908 Letters Patent established constitutional arrangements for its possessions in the South Atlantic, including the formal annexation of the South Sandwich Islands. The Letters Patent listed these possessions as "the groups of islands known as South Georgia, the South Orkneys, the South Shetlands, and the Sandwich Islands, and the territory known as Graham's Land, situated in the South Atlantic Ocean to the south of the 50th parallel of south latitude, and lying between the 20th and the 80th degrees of west longitude". In 1917 the Letters Patent were modified, applying the "sector principle" used in the Arctic; the new scope of the Falkland Islands Dependencies was extended to comprise "all islands and territories whatsoever between the 20th degree of west longitude and the 50th degree of west longitude which are situated south of the 50th parallel of south latitude; and all islands and territories whatsoever between the 50th degree of west longitude and the 80th degree of west longitude which are situated south of the 58th parallel of south latitude", thus reaching the South Pole. The 1908 Letters Patent were not disputed by Argentina at the time, but in 1948 Argentina conceived an argument that they were invalid on the grounds that they allegedly encompassed parts of the South American mainland as well as the Falklands, making the latter dependencies of themselves.