OSNAPZ

Sometimes drawing in 3D can be a little puzzling, especially if you're looking at 3D objects in orthographic views. Say you have a wireframe cube that you're looking at in Plan view, and you want to draw a line between two diagonal corners on the top of the cube. Using object snaps to pick the corners, as often as not you'll find that you have a line that's not on the plane of the top of the box, but starts at a top corner and ends at a bottom corner. One way around this problem is set the OSNAPZ variable appropriately. By default, OSNAPZ is set to 0, which means AutoCAD will find the X-, Y-, and Z-coordinate of the snapped-to point. But often you don't want that to happen. Set OSNAPZ to 1, and AutoCAD replaces the Z-value of the picked point with the current elevation — or the Z-value of the first point picked.

Since OSNAPZ only affects drawing in three dimensions, it's not available in AutoCAD LT.