The _ExtremesConfiguration type exposes the following members.
Gets or sets the background color of the series extremes.
Gets the the color of the border. Accepts a valid CSS color string, including hex and rgb.
Gets or sets the rotation angle of the extremes.
Gets or sets the marker size in pixels.
Gets or sets the extremes shape. The supported values are: "circle" - the marker shape is circle. "square" - the marker shape is square. "triangle" - the marker shape is triangle. "cross" - the marker shape is cross.
If set to true the chart will display the series extremes. By default chart series extremes are not displayed.