ps-spool-duplex

ps-spool-duplex is a variable defined in `ps-print.el'.
Its value is

nil

Documentation:
Non-nil generates PostScript for a two-sided printer.
For a duplex printer, the `ps-spool-*' and `ps-print-*' commands will insert
blank pages as needed between print jobs so that the next buffer printed will
start on the right page. Also, if headers are turned on, the headers will be
reversed on duplex printers so that the page numbers fall to the left on
even-numbered pages.

See also `ps-spool-tumble'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 20 of Emacs.