System and Plotter Layers
A font must support mirroring, rotation, and scaling to be capably rendered on a photoplotter. There are two categories of layers as they relate to the ability to plot a font.
System Layers
System Layers text does not need to be plottable. The stackup, service, and user layers are system layers.
Plotter Layers
Plotter Layers text must be capable of being plotted. All layers that are not system layers are plotter layers.