The data model used by chart components.
 The chart is draw using values from the yValues 2D array. The yValues are returned by
 
getYValues() method. The maximum and the minimum are controlled by 
 
getMaxYValue() method and 
getMinYValue() method. The default maximum value
 is 120% of the maximum of the yValues if no value is specified. The default minimum value 
 is 0. For XYLine and Scatter plots xValues are also required. The xValues are controlled by
 
getXValues() method, 
getMaxXValue() method and 
getMinXValue() method.
 
 The labels on y-axis of the graph are calculated from the yValues. However the labels on the
 x-axis are controlled by the group labels array returned by  
getGroupLabels() method.
 
 Each group of values in the chart may contain multiple series. The number of series in a
 group are controlled by 
getSeriesLabels() method. 
 
 The colors of the series are controlled by 
getSeriesColors() method.
 
 The chart title, sub-title and the footnote can be specified using 
 
getTitle() method, 
getSubTitle() method and 
getFootNote() method