Bonded Area (保税区), also known as Bonded Warehouse Area, are economic areas approved by the State Council and supervised by China Customs, which serve 3 main functions: bonded warehousing, export processing, re-export trading. These areas benefit from certificate exemption, duty free, and bonded policy, and implement the operation mode within national territory but outside customs territory (境内关外), making them China's economic regions with the highest degree of opening to the outside world, the most convenient operating mechanism, and the most favorable policies. In June 1990, the Chinese government decided to establish the first bonded area in Shanghai, which is called Shanghai Waigaoqiao Bonded Area. Since 1992, the State Council has approved to establish a further 14 areas in Tianjin, Dalian, Zhangjiagang, Shenzhen, Fuzhou, Haikou, Xiamen, Guangzhou, Qingdao, Ningbo, Shantou, and Zhuhai, as well as one Economic Development Zone, i.e., Hainan Yangpu Economic Development Zone, that shares the same bonded policy. The Shanghai bonded area remains the one with the largest economic aggregate among the 15 bonded areas across the country.