Determines the type of [[Series]].
Area; used by both area and area 3D charts.
Bar; used by both bar and bar 3D charts.
Bubble.
Line; used by line, line 3D, and stock charts.
Pie; used by pie, pie 3D, doughnut, and 'of pie' charts.
Radar.
Scatter.
Surface; used by surface and surface 3D charts.
Determines the type of [[Series]].