A load extending beyond the back of the vehicle must be marked. Which means are allowed during the day?

You answered correctly. When a load extends beyond the rear of your vehicle during the day, German traffic rules require it to be clearly marked to warn other road users. This can be done either with a bright red flag of at least 30 x 30 cm held apart by a crossbar, or with a bright red sign of at least 30 x 30 cm, mounted so it hangs across the direction of travel. An orange warning plate is not permitted for this purpose during the day. Knowing these allowed marking methods is important for safety and to comply with legal requirements.