The Boundaries of Macau, officially the Delimitation of the administrative division of the Macao Special Administrative Region of the People's Republic of China[1] (Portuguese: Delimitação da divisão administrativa da Região Administrativa Especial de Macau da República Popular da China, Chinese: 中華人民共和國澳門特別行政區行政區域界線), is a regulated administrative border with border control controlled by the Public Security Police Force in force under the One country, two systems constitutional principle, which separates the Macau Special Administrative Region from mainland China, by land border fence of 0.34 km (0.21 mi) and maritime boundary of 85 km (53 mi),[1] enforcing a separate immigration and customs-controlled jurisdiction from mainland China.