There are four kinds of health certificate ABCD, each corresponding to different industries, as follows:
Class A: Physical examination of employees in catering industry, food factory, canteen, water plant and water dispenser factory.
Class B: Physical examination of employees in tourism, culture and entertainment, beauty salons, shopping malls, cosmetics factories and health centers.
Class C: Physical examination of general occupational recruitment in general factories and enterprises.
Class D: Physical examination of electricians, elevator workers, boiler workers and other high-temperature aerial workers.