During my last trip to France via car I noticed that French freeways (autoroutes) have a somewhat strange road marking I am not familiar with.
Usually, there are two lanes going my direction on a freeway. These lanes are separated by a dashed line indicating I am allowed to cross this line to pass cars by moving to the left lane.
A few hundred meters before each exit the frequency of these dashes changes. They are much closer together but still don't form a solid line. As soon as the exit is passed, the line changes back to dashes spread further apart, just as before.
In case you do not know what I mean, have a look at e.g. this freeway exit near Paris on Google Maps.
What do these dashes near the exit mean? Am I supposed to not change lanes in this area?