Reference Lines help you to highlight particular areas or values in Vizlib Ridgeline Plot.
If you add a reference line (Figure 1) a count will display beside the settings, so Reference Lines(2) would indicate 2 reference lines have been added to the chart.
Figure 1: Reference Lines
When you open the reference line settings (Figure 2), you can enter a Dimension Value (text or expression), add a Label, set the Font Color, Font Size, Text Opacity, Font Style, Label Position and Label Align.
Figure 2: Label
If you enable Outline settings (Figure 3), you can set the Outline Background, Outline Border, Outline Stroke Width and Outline Border Radius.
Figure 3: Outline
Line settings (Figure 4) control the Line Color, Line Thickness, Line Opacity, Line Style and Line Position.
Figure 4: Line