Manual missing sections

[Bioman]

I see that the manual does cover any fortifications in any way. There is no picture of what they look like nor any info on what effects they have in the game. I am playing a scenario that has caves and it would be nice to know what they do. Do they allow special movement, special combat results or maybe special detection rules? I was able to find a listing for caves in the WW2 campaign series. Do they work the same or differently?