Canon Pixma iP90 User Manual page 120

Margin (Print Dialog Box)
If you select Margin from the pop-up menu in the Print dialog box, you can
set a staple margin.
(1) Stapling Side
Select a stapling side from Left, Right, Top, and Bottom.
(2) Margin
Specify the staple margin with a value between 0 mm and 30 mm.