[]
Gets or sets the location of the summary columns in the outline.
Use this property to determine whether the summary column is displayed to the left or to the right of the detail columns in a column outline.
SummaryColumn SummaryColumn { get; set; }
Property SummaryColumn As SummaryColumn
worksheet.Range["A:C"].Group();
IOutline outline = worksheet.Outline;
outline.SummaryColumn = SummaryColumn.Left;
SummaryColumn summaryColumn = outline.SummaryColumn;