You unhitch your caravan on the hard shoulder along the A28 near Dwingeloo and leave it standing there separately at night while you fix a breakdown on the car. Does the sidelight duty also apply to the unhitched caravan?
Yes, the duty also applies when detached from the car
No, once unhitched the caravan falls outside the lighting duty
Explanation
False — trap: duty tied to the coupling instead of to standing still. The book explicitly states it does not matter whether the trailer is attached or unhitched (Book p.186).