Order Property
From Microsoft Office Web Components Object Model
Order Property
Returns or sets the polynomial order for the specified trendline (an integer value greater than 1). If you set this property for a linear trendline, it becomes a polynomial trendline. Read/write Long.
expression.Order
expression Required. An expression that returns a ChTrendline object.
Example
This example sets the order for the specified trendline.
ChartSpace1.Charts(0).SeriesCollection(0).Trendlines(0).Order = 2