What is a "cheater plot"?

The layout -> yaxis -> visible docs refer to a “cheater plot” but I do not know what this is. It seems to be referenced elsewhere too, e.g. in the carpet plot (link is to Python API) so I don’t think it’s an error in the documentation.

yaxis

visible (boolean)
A single toggle to hide the axis while preserving interaction like dragging. Default is true when a cheater plot is present on the axis, otherwise false

Here’s a cheater plot: https://rreusser.github.io/plotly-mock-viewer/#cheater which has its own a/b axes but it drawn on top of an x/y subplot.

So a cheater plot is a plot that is just overlaid on top of another one? (It’s values don’t correspond to the X/Y axes shown.)