How long a vehicle with small yellow license plates can a C1 license drive?

[Furtado]

C1 license holders cannot drive vehicles with small yellow license plates; they are only permitted to drive vehicles under six meters in length. Below is more information about the C1 license: 1. Vehicles not allowed for C1 license holders: large buses, tractors, city buses, medium-sized buses, large trucks, ordinary three-wheeled motorcycles, ordinary two-wheeled motorcycles, light motorcycles, wheeled self-propelled machinery, trolleybuses, and trams. 2. Permitted vehicle types: small and mini passenger vehicles, as well as light and mini cargo vehicles, light, small, and mini special purpose vehicles. 3. C1 license holders cannot drive vehicles with more than 9 seats. 4. The total length of the driven truck must not exceed 6 meters. 5. The examination subjects include four items: traffic regulations and related knowledge, field driving, road driving, and safe and civilized driving common sense.