Epson Stylus Color 980 Manual page 35

Once the Double-Sided Printing check box is selected, it is
possible to make the following double-sided printing settings.
Margins
Click this button to open the Margins dialog box, where you can
specify which edge the binding will be on. You can choose
between Left, Top, and Right. You can also specify the width of
the binding margin by entering a value in the Binding Margin text
box.
Folded Booklet
Select this check box to make single-fold booklets. For more
details on this feature, refer to "Making the Layout menu settings"
on page 3-23 for Windows, or "Making the Page Setup settings"
on page 5-12 for Macintosh.
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Double-Sided Printing