What is the mandatory 'zip merging' rule (Reissverschlussprinzip) on Swiss motorways when a lane ends or is blocked?

1. Drivers must merge 2 kilometers before the obstruction and block the ending lane
2. The lane with fewer trucks always has priority
3. Drivers in the ending lane must drive up to the point of closure, where alternating vehicles from each lane take turns merging smoothly
4. Drivers on the continuous lane may accelerate and aggressively prevent ending-lane vehicles from merging