Technical Reference
Page 184
... later of LEXPS Windows 3.x Version 4.02 or later of the Lexmark Optra S driver which sends the PostScript command to switch to backward compatibility mode. (The original Lexmark Optra S driver does not send this mode. For backward compatibility with the Lexmark Optra S family of printers, use . 4-16 PostScript Your printer defaults to the forward compatibility mode and the Lexmark PostScript driver uses this command...
... later of LEXPS Windows 3.x Version 4.02 or later of the Lexmark Optra S driver which sends the PostScript command to switch to backward compatibility mode. (The original Lexmark Optra S driver does not send this mode. For backward compatibility with the Lexmark Optra S family of printers, use . 4-16 PostScript Your printer defaults to the forward compatibility mode and the Lexmark PostScript driver uses this command...