The topic has been discussed here in the Netherlands, and found an answer summarized in the below chart (sorry, it is in Dutch, but the flow and the picture should be understandabletext translated into English from the original).
The title is "Are you ready for the night?"
Translation of the captions:
- (top left) What is the color of your front light?
- (above the cake) decorate a cake with it
- (2nd from the top, left) How do people coming from the opposite direction look like?
- (3rd from the top, left) How do you look like?
- (3rd from the top, right) Where do you bike the most?
- (4th from the top) How does your bike look like?
- (5th from the top, right) Fancy, but not allowed
- (bottom black arrow) In this way you bike safely in the night
Wrapping up: lights should be fitting the standards and fulfill their scope. No blinding, no lighting up in the sky or down the floor, no fancy colors.

