Comment by layman51

Your post reminded me of a video on the an imported TVR Tuscan, filmed by Doug DeMuro where he covers this too. The TVR Tuscan is one of those cars where if the rear trunk is open, you can’t see the turn signal lights. In the video it is claimed that because of that, by laws in the UK, the trunk must have a triangular exclamation point sign as a safety precaution to let other drivers know when the vehicle is immobile.

That is around the seven minute mark of this video: https://www.youtube.com/watch?v=32u6KPTALxg