postscript prologue

Each PostScript output file includes a %%Prolog section and possibly some additional user-defined sections containing, for example, character encodings. These sections are copied from a set of PostScript prologue files that are either compiled into the gnuplot executable or stored elsewhere on your computer. A default directory where these files live is set at the time gnuplot is built. However, you can override this default either by using the gnuplot command set psdir or by defining an environment variable GNUPLOT_PS_DIR. See set psdir.