Cool tool the Shaft Opening, it cuts floors, ceilings and roofs that it comes into contact with. It also provides a way to display symbolic lines within the sketch so you can generate graphics to indicate openings more efficiently than drawing them separately or using detail components.
This post is concerned with the display of symbolic lines when you don't expect them to appear. If the View Range setting for Top-Offset of a level below a Shaft Opening has a Top-Offset setting that is high enough to intersect with the Shaft Opening the symbolic lines will appear. They will appear even if the shaft itself doesn't interesect with the cut plane of the lower level. Here's the view Range dialog and the Top Offset is set higher than the level above (11'-0" above Level 1).
In my perfect world a shaft would not show symbolic lines unless the cut plane of the view intersected the shaft, not the primary range itself. Fortunately the instances I've encountered are usually due to unnecessarily high settings of the Top-Offset value.
Added THIS POST to the HOK CAD Solutions Blog.