Do not use these modules in new programs. They are likely to disappear in a (distant) future release. Use plot, plot/utils, plot/no-gui, plot/bitmap and plot/pict instead.
Plot versions 6.1.1 and earlier were written in untyped Racket, and exposed a typed interface through these modules. Now that Plot is written in Typed Racket, a separate typed interface is no longer necessary. However, the above modules are still available for backwards compatibility.