I wish to confirm that I understand the Cave LOS rules correctly. The first image shows the map area without the Cave counters. The second image shows the map with two Cave counters. It also has two "LOS threads". I believe that the red one is blocked and the gray one is clear. What do you think?
I agree. The gray line is a continuous slope. The G11.12 example Cave A is basically the same. Red Line, no LOS to more than M5 and L5 along that line.
Just to clarify that, while it is true that the gray line forms a continuous slope and is therefore eligible for fire lane placement, any unit in cave FF also has LOS to all non-blind hexes in its covered arc that do not cross L5.