OptionaloverlayThe price pane, in the instrument's own units, staying there when the
study moves. A shape is measured on the scale that pane quotes prices on
(its crosshair readout, which is the candles' own scale on whichever axis
they sit) and holds no axis itself, so the price axis stays free to move.
A marker is anchored to the instrument's candles, so belowBar sits
under the low; it is drawn once the chart has a primary series. A shading
column fills the price pane's full height and binds no axis. Naming a
plot as well is rejected: a plot already decides its pane.
OptionalplotA declared plot key. A shape is drawn on that plot's pane and measured on
its effective price scale; a marker is anchored to that plot's series, so
aboveBar and belowBar read its values, and where it has none, the
candle's whenever that plot is on the price pane and on the candles' scale,
first plot or not. A shading column fills that plot's pane and is bound to
its effective scale, which has no price to measure but keeps the layer on
the axis the plot uses, so a reassignment never leaves a column held for
nothing. Each follows the plot through a scale reassignment or a study
move. An overlay plot takes it to the price pane.
One column of per-bar shading a study's
backgroundreturns in its list form, optionally sent to another pane or plot.colorsis what the plain form returns: one entry per bar,nullwhere nothing is shaded.