The De Ceremoniis (fully De cerimoniis aulae Byzantinae) is the conventional Latin name for a Greek book of ceremonial protocol at the court of the Byzantine emperors in Constantinople. Its Greek title is often cited as Ἔκθεσις τῆς βασιλείου τάξεως ("Explanation of the Order of the Palace"), taken from the work's preface, or Περὶ τῆς Βασιλείου Τάξεως ("On the Order of the Palace"). In non-specialist English sources, it tends to be called the Book of Ceremonies of Constantine VII Porphyrogennetos (variably spelt), a formula used by writers including David Talbot Rice and the modern English translation. Source: Wikipedia (en)