De Ceremoniis
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 ("Explanation of the Order of the Palace"), taken from the work's preface, or ("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.