  Daniel Delattre’s work (2007) on the pieces of papyrus now securely attributed to On Music IV, Dirk Obbink’s on the first half of On Piety (1996), and Richard Janko’s on On Poems [I] showed how to ‘reconstruct’ bookrolls, by identifying which items in the catalogue of papyri belong to a given roll, working out their original locations within it, and re-ordering the copies of their fragments.