What does C1D mean on a driver's license?

[RubyRose]

C1 and D driver's licenses refer to a combined license that permits driving both C1 and D vehicle categories. The C1 license allows driving small cars, while the D license permits operating ordinary three-wheeled motorcycles. C1: Small cars, small automatic transmission vehicles, low-speed cargo vehicles, and three-wheeled vehicles. Small and micro passenger vehicles, as well as light and micro cargo vehicles; light, small, and micro special-purpose vehicles; small passenger vehicles with a seating capacity of 9 or fewer people. D: Three-wheeled motorcycles, ordinary two-wheeled motorcycles, and mopeds with an engine displacement exceeding 50ml or a maximum design speed exceeding 50km/h. Application age: The minimum age requirement for a C1 driver's license is 18 years old, with no upper age limit. The application age for a D driver's license is between 18 and 60 years old.