And I'm saying that if a prone model at higher elevation turns its back towards its enemies, it will not be able to draw LOF and since there is not a 3x3mm perpendicular plane inside this model's silhouette due to trigonometry (the floor this elevated model is standing on will block it), then no one on lower elevation will be able to draw LOF to the elevated model, either. Meaning there is no awareness that can be mutual. That's an assumption you can make about all of CB's rules, but the problem is that quickly the rules become meaningless and all you're left with is a huge set of house rules. I find CB's language regarding LOF to be unusually consistent, however, with the only caveat being that the 3x3mm visibility condition being poorly defined, but to each their own. That's assuming you've got enough orders to put the Intruder into marker state. But whether it's an Intruder, a Nisse, a Yan Huo, or otherwise is irrelevant to the example as long as it is a model you don't want shot in the reactive turn and that it can go prone.