This opens a whole host of questions about Lines of Forbiddance (and other lines). Can one direct the Line of Forbiddance or is it always perpendicular? And what is it perpendicular to? If you draw a Line of Forbiddance on a slope, is it perpendicular to the slope or to the Earth? Could you create a sloped line which you could walk across? Anchor it in whatever appropriate way, then walk across it. Cheap bridge, cheap way over
Can Lines be created which are not anchored to the Earth? Could you create a square of Line of Forbiddance on a slate, flip it over, and set it down as a cage over Chalklings (or a person or whatver)?