Heidegger's Bible Handbook: Old Testament in General: Medium Divisions
4. The medium Sections. The סדרים/Sedarim, and their use. The Medium Sections the Hebrews call סדרים/Sedarim, Orders, or sections briefer than the Parashot, inserted by the Masoretes into the Sacred Books, so that according to the coherence or diversity of matters those texts might be separated through all the Books of the Old Testament by which they are shared. Thus, for example, while Genesis has twelve Parashot, the same has forty-three Sedarim.
 The Masoretes were mediæval Jewish scribes (laboring from the fifth to the tenth centuries AD), responsible for the preservation and propagation of the traditional text of the Hebrew Scriptures.