The term Byzantine music is sometimes associated with the medieval sacred chant of Christian Churches following the Constantinopolitan Rite. There is also an identification of "Byzantine music" with "Eastern Christian liturgical chant", which is due to certain monastic reforms, such as the Octoechos reform of the Quinisext Council (692) and the later reforms of the Stoudios Monastery under its abbots Sabas and Theodore. The triodion created during the reform of Theodore was also soon translated into Slavonic, which required also the adaption of melodic models to the prosody of the language. Later, after the Patriarchate and Court had returned to Constantinople in 1261, the former cathedral rite was not continued, but replaced by a mixed rite, which used the Byzantine Round notation to integrate the former notations of the former chant books (Papadike). This notation had developed within the book sticherarion created by the Stoudios Monastery, but it was used for the books of the cathedral rites written in a period after the fourth crusade, when the cathedral rite was already abandoned at Constantinople. It is being discussed that in the Narthex of the Hagia Sophia an organ was placed for use in processions of the Emperor's entourage.