Yadayim, Chapter Three, Mishnah Four
1) The margin on a scroll which is above or below or at the beginning or at the end defiles the hands.
2) Rabbi Judah says: the margin at the end does not render unclean [the hands] until a handle is fastened to it.
Section one: Although there is nothing written in the margins of the Tanakh scrolls, they still defile the hands because they are part of the scroll.
Section two: Rabbi Judah says that the margin at the end of the scroll doesn’t defile because it could always be cut off. It only defiles once they have used that extra piece of scroll to attach a handle. Once a handle has been attached the end margin has become a necessary part of the scroll and it too defiles.