special administrative region

A special administrative region is a part of China that retains its own legal system, currency, customs territory and immigration control. There are two, Hong Kong and Macau.

Each sits directly under the central government at the level of a province, and neither belongs to any province.

Their separateness reaches into the data. Hong Kong and Macau keep their own statistics offices, their own registers and their own address systems, so a Chinese national code series does not cover them.