DUPLEX = <option>
(Windows only, but see final paragraph below) This function enhances duplex printing. Option may be H{orizontal} or S{hort} for short edge binding, or V{ertical} or L{ong} for long edge binding. Anything else disables duplex printing.
DUPLEX is one of the printer ini file commands that has a GDI Printing Directive Equivalent.
Note that although DUPLEX is only supported directly by A-Shell under Windows, you can effectively support a duplex option in Unix by creating multiple versions of your printer init command which include the required lpr command line options in the DEVICEpq directive.
