Asus R300 User Manual page 54

The line of the route is displayed on the driving side of the road for two-way and on the axis
in case of one-way streets. When the map is zoomed in and the line is wide enough, small
arrows show the direction of the route. This can be useful if you preview the route before
starting the journey or when entering a complex junction.
Inactive legs of the route
Future sections of a route are inactive. They are also shown on the map with the same
colour but a darker tint than the active one. An inactive route section becomes active as
soon as you reach its starting Via point.