The priority road bends Voorrangsweg maakt een bocht
De regel · The rule
When the priority road bends, you keep priority if you follow it, but you still signal, because you change direction.
sign B1 · RVV 1990 art. 17

Why this rule exists
Others see you turn and must know whether you follow the main road or leave it.
Test yourself
Kees' three questions on this rule, the “Wist je dat?” facts and his tip come with the drive, in Voorrah! Pro.