Show empties

If this box is checked, all the possible values for a particular field will be displayed regardless of whether or not data fell in that category.  For example, if a Type of Collision chart has values of 3-sideswipe; 5-head on; 0-right angle; 17 rear-end; and 0-overturning, the option exists of whether or not to show a bar for right angle and overturning accidents.  Typically, these bars would be left out of a chart.  One situation where showing them would be handy is in a time of day or month of year chart.  In this case, the chart would look odd without the empty bars.