In the Corners section of p12.

It basically says if you are standing next to the corner - you can see around it. That would imply that you can see all the way down the corridor (as long as you are standing at the corner) - though the picture shows a genestealer only the in the very closest square. If the genestealer in that diagram moved back one space, could the terminator still see him? - what do you guys think. I think, yes.