Sets or returns the outline level of the row, as a value between 0 and 7. The outline level is used to control grouping in Excel. For example, to group several rows, set their outline levels to 1; to group a subset of rows within the group, set their outline levels to 2.

public int OutlineLevel{ get; set; }
Public Property OutlineLevel() As Integer
          //--- Get OutlineLevel
          int level = rowProps.OutlineLevel;

          //--- Set OutlineLevel
          rowProps.OutlineLevel = 4;
          '--- Get OutlineLevel
          Dim level As Integer = rowProps.OutlineLevel

          '--- Set OutlineLevel
          rowProps.OutlineLevel = 4