Treaty of Taipei
In regards to the origin of the term, Lee explained in 2005 during a lecture in that, following World War II, Chiang Kai-shek's forces temporarily occupied the island of Taiwan under the direction of Supreme Commander for the Allied Powers Douglas MacArthur, and because both the Treaty of San Francisco and the Treaty of Taipei concluded afterwards did not explicitly specify to whom Japan renounced the sovereignty of Taiwan, the legal status of Taiwan has become undetermined, and that's why he coined the term "Republic of China on Taiwan".