Selecting the View - Fence - Zoom command causes the rectangle cursor to appear. To zoom in an area of the model:

1. Move the mouse to one corner of the area to be zoomed in.
2. While holding down the left mouse button, drag the mouse to the opposite corner of the desired area.
3. Release the mouse button.

The screen will redraw with the selected area enlarged so that the fenced area occupies the entire screen.