The Assigned and Unassigned list boxes display assigned or unassigned I/O macros in the design. By default, all assigned I/O macros are displayed in the Assigned list box and all unassigned I/O macros are displayed in the Unassigned list box.
You can filter which pins are displayed in these list boxes. To customize the Assign and Unassign list boxes, from the View menu, choose Configure List Boxes.