invokes Ghostscript, an interpreter of Adobe Systems' PostScript(tm) and Portable Document Format (PDF) languages.
is a filter used by CUPS to convert PostScript to a generic raster image format that is acceptable as an input to drivers for non-PostScript printers (e.g., from Gimp-Print-4.2.7). It is built and installed only if CUPS-1.2.7 is found.
ESP Ghostscript provides many different scripts used to render PostScript/PDF files back and forth. Please refer to the HTML documentation or try man gs for information about the capabilities provided by the package.