Mishnayos Gittin Perek 9 Mishnah 7

If a scribe left out part of the bill of divorce and wrote it in the second column, i.e., the bill of divorce is written in two columns on one paper, and the signatures of the witnesses are beneath the second column, it is a valid bill of divorce. If the witnesses signed at the top of the column, on the side, or on the back of an ordinary, non-folded bill of divorce, it is invalid. If the scribe placed the top of this bill of divorce next to the top of that bill of divorce so that both are written in the same column but with the text in opposite directions, and the witnesses signed in the middle, between the bills of divorce, both bills of divorce are invalid. If he placed the end of this bill of divorce next to the end of that bill of divorce, and the witnesses signed in the middle between them, the bill of divorce with which the witnesses’ signatures are read, i.e., the bill that is written in the same direction as the signatures, is valid. If he placed the top of this bill of divorce next to the end of that bill of divorce, and the witnesses signed in the middle, the bill of divorce at the end of which the witnesses are read, i.e., the upper bill of divorce, is valid.