I recognize the official system for French waymarks of Grand Randonees and local paths like shown here: but I've also seen large white rectangles with a horizontal red line in the middle. They are much larger than traditional waymarks. I've seen them in several areas, and there are often quite a few along a short part of the trail. What do they mean?
I've also seen with one rectangle with a much smaller white circle with a red dot in the middle below it, but just once.