The liturgical book called Octoechos (Greek: —the name contains ?κτω = eight, and ?χο? = echos, while the female form is only used for the book ; Slavonic: Октоихъ, Oktoikh, or Осмогласникъ, Osmoglasnik) contains a repertoire of hymns ordered in eight parts according to the eight echoi (tones or modes). Originally created as a hymn book with musical notation in the Stoudios monastery during the 9th century, it is used until nowadays in many rites of Eastern Christianity.