Load and trailer
About The marker board: who, when, how big?: which statement is WRONG?
On every trailer a marker board is always required, regardless of the load.
The marking-board requirement applies to the trailer, not to the passenger car itself.
The marking board is RED-AND-WHITE diagonally striped and retroreflective.
The legal MINIMUM is a square board of 0.42 x 0.42 m; 50x50 is only a common commercial size, not the legal floor.
Explanation
Book p.229 - the board is required at side >10 cm OR rear >1 m protrusion; without that protrusion there is no board duty.
Practise this question in the app