What does a license plate starting with 'hn' mean?

[DeReagan]

A license plate starting with 'hn' belongs to the General Armament Department. Civilian license plates do not have categories that start with letters; all civilian license plates begin with Chinese characters. The Chinese character on a civilian license plate represents the province or municipality directly under the central government, and the letter following the first character represents the city or district. A license plate, commonly known as a vehicle plate, is a panel hung on the front and rear of a vehicle, usually made of aluminum, sheet metal, plastic, or paper, inscribed with the vehicle's registration number, registration region, or other relevant information. License plates serve as a numbering and information registration system for vehicles, with the primary purpose of identifying the vehicle's region of registration and enabling the tracking of the vehicle's owner and registration details based on the plate number.