Set OS 31 = 0 (and OS 1 = 3275) to place multiple isometrics all in one plot file. This is the most economical method when the plot files are going to a paper roll type plotter.
Set OS 31 = 1 to place each isometric in a separate plot file. Use this option when plot files are in DXF or DGN format for loading into a 2D graphics system or when plot files are going to a laser printer.
Set OS 31 = 2 to send the isometric directly to the screen.
This option does not work on a PC.