Thus, if a format groups the values, the procedure uses those groups.
Class variables can be numeric or character.
Class variables can have continuous values, but they typically have a few discrete values that define the classifications of the variable. You do not have to sort the data by class variables. The values of the class variables appear in the listing. Therefore, the output typically is more meaningful if you sort or group the data according to values of the class variables. In this case, the listing of the plot variable contains a column for each value of the symbol variable, and each row of the plot contains a point for each value of the symbol variable.