Recently, I received a drawing made in 3D for editing. All my lines and polylines take a default Z height. I can however reset the thickness to zero in the properties dialog area of the lines, but I'm at a loss on whether this kind of 3D environment was created by specifying the thickness of model space or, through a kind of guru(aic) wiz done with layers (don't blame me, I see "miracles" everyday in the forums).
There are only four (4) layers in the complete drawing, all starting with the letters 3d... Do these have anything to do with the 3D behaviour?