Australian Citizenship by Birth (Papua New Guinea)
If you were born in Papua New Guinea BEFORE independence was granted on 16/09/1975 and one of your parents was an Australian Citizen (or Australian Passport holder) at the time of your birth AND they themselves were born in Australia, then an application can be made for Citizenship. Once that is approved, an application for a passport can be made.
Up until 16/09/1975, Papua New Guinea was a colony of, and under the jurisdiction of, Australia. Many thousands of Australians were resident at the time, hence this special dispensation.