The zoom window appears at the bottom portion of your workspace window, magnifying the area around your current cursor position. As you move your pointer across your ceph, the zoom window focus changes so that the area you are working on is centered.
Magnification ratio - You can alter the magnification ratio between the ceph and the zoom window to gain additional accuracy while tracing. See "Set Up Trace Options" for details
Enable / disable markings - You can enable / disable structure markings in the zoom window. See "Set Up Trace Options" for details.