What can a flashing blue light (without siren) mean?

The combination you selected is correct because it aligns with German traffic regulations regarding the use of a flashing blue light.

1. When a vehicle displays a flashing blue light, it indicates that the vehicle is on duty for emergency services, and other road users must yield the right of way to ensure the vehicle can proceed safely.

2. The flashing blue light can also serve as an advance warning of a closed convoy. In such cases, vehicles are often transporting important individuals or materials, and it’s crucial for other road users to be aware and maintain distance.

It's essential to recognize both aspects because simply yielding to emergency vehicles ensures safety on the road, and being aware of a convoy allows for proper traffic management. Not understanding the implications could lead to dangerous situations or traffic violations.