Use this dialog box (from the Thematic Mapping dialog box) to specify the source of thematic data and then select one or more discrete values from that data.
Click . In the Choose Data Expression dialog box, select the source of the data to use.
Select data values to exclude from the thematic display. These values, while present in the data, may be inappropriate for use in the thematic map. Examples include null or empty data values.
Enter a value or an expression if you want to normalize the data values relative to some other data value. Click to display the Choose Data Expression dialog box.
Reads the data from the data source according to the expression you defined.
Shows the values read from the data source, together with the number of occurrences (Count). Select the value(s) to appear in the thematic map. To quickly select all the values, right-click and choose Select All.