also: FIB · formation into boundary
Formation into the boundary means the offense sets its strength to the short side of the field. Teams may use it so they can motion a receiver toward the field and catch the defense out of position.
Scout film with properly tagged clips can help you see whether a team is doing this intentionally to gain an advantage. Your first clue is often lots of motion when the team aligns on a hash. If this is happening, check whether the play's Hash column often matches its tagged Strength when those motions occur.