Click the box next to or below an option to select or clear the check box (shown in Figure 4-3). When you click an empty box, a check mark or an X appears in the box. If you click a box that is selected, then the check mark or X disappears.
In query mode, check boxes have a third possible state. For more information about using check boxes in query mode, see "Tips for Queries."
You can press the space bar to select and deselect check boxes.