The four inner quadrants contain: "Petrus," "Paulus," the pope's name, and the pope's ordinal number. The current pope's motto surrounds the outer circle. The inside of the outer circle sometimes contains the pope's autograph.
The rota was also used by monarchs for the authentification of administratives documents and diplomas.
^For instance it was used by William I of Sicily (image) and William II of Sicily : Antonia Gransden, Legends, traditions, and history in medieval England, Continuum International Publishing Group, 1992, p. 184