The mechanical register unit on a printing press that positions a sheet from the side.
The guides on the sides of the sheet fed press that position the sheet sideways as the paper is led towards the front guides.
On sheet-fedpresses, a guide on the feed board to position the sheet sideways as it feeds into the front guides before entering the impression cylinder.
A guide on sheet-fed presses that positions the sheet sideways as it feeds it into the front guides before entering the impression cylinder.