Bava Batra 160 - Document That is Folded and Sewn Down
Two kinds of documents are "plain" and "folded," or "bound." A plain document is written in the usual fashion, the pertinent information being written in a single, unbroken body of text.
Folded, or "bound" document is written in the following manner. The scribe writes the first line and leaves the second line blank. He then folds the written line forward onto the blank blank and sows ("binds") the fold shut. He then repeats this process for subsequent lines.
The Sages created the "bound" document, which was very hard to produce, to prevent Kohanim from rashly divorcing their wives. A Kohen cannot remarry his wife, because she becomes a divorcee. Now that he is first required to find a scribe who knows how to produce a "bound" Get, he will make peace with her. Commercial documents can also be "bound." Not widely used even in the time of the Mishna, the "bound" document went completely out of use by the 10th century.
Art: John Frederick Lewis - The scribe