Overlay graphs are graphs that are laid on top of the main graphs.

Overlay graphs are available for the following primary graph types, all in 2D form only:

Area
Bar (vertical)
Candlestick
High-low-close
Line
Open-high-low-close
Scatter

An overlay graph is always a line / scatter graph.

Important: If a legend is to be used for the main graph, a legend entry for the overlay graph must be provided in the OVERLAYLEGEND attribute.

In addition there are several other properties that allow you to customise the overlay graph. These can be found in the Common Attributes list.