Originally Posted by eaglesrest

It's like setting a waypoint. It makes sure that the route planner takes you via the specified route magnet.

For example, if you want to go from A -- B, the route is calculated.Lets say you don't like the route it calculates because you know that one of the roads on the list has major roadworks. You can then use route magnet to specify a waypoint on a different road that would ensure yu bypass the roadworks.