Occasionally, you will make a mistake while you are zooming, panning and rotating and lose the part of the cave you were trying to view. For this reason, the Viewer is constantly saving previous views of the cave so they can be restored. The Viewer saves last 500 pan, zoom, rotation and viewing angle changes. This means that you can "undo" the last 500 changes and restore old views of the cave. You do this by click-on the “Undo” button on the Tool Bar.
You can also select the "Action->Undo Last Zoom/Pan/Rotation " option from the menu bar or type the "U" key on the keyboard. Each time you perform the undo command, the program steps back to the previous view of the cave. Since the program only stores the last 500 commands, you can only do this 500 times.