The litany Kyrie eleison is usually the first item in settings of the Ordinary of the Mass and is said to have been introduced into the Latin Rite by Pope Sergius II. The Greek text is a 9-fold invocation (Kyrie eleison, Kyrie eleison, Kyrie eleison. Christe eleison, Christe eleison, Christe eleison. Kyrie eleison, Kyrie eleison, Kyrie eleison.) and is sometimes sung or set alternatim, that is with one choir or the organ beginning and a second choir singing the even-numbered repetitions. The 1970 Novus Ordo reduces these to 6.
A mediaeval practice was to insert tropes or extra text. This survived in the Sarum Rite, and polyphonic Communion Services by English composers usually omit the Kyrie, which would be treated as proper to the day. A Lutheran survival is Kyrie Gott Vater in Ewigkeit, based on the trope fons bonitatis. In other countries the numerous Gregorian melodies continued to be identified by the formerly associated tropes as well as local custom and order in publications. Thus Kyrie cunctipotens genitor is identified by Couperin as "pour les paroisses" ("for parish use"), by Frescobaldi as de Apostolorum (for Feast of Apostles) and appears as number IV in the Vatican Edition, while Kyrie orbis factor is Kyrie IX of the Sarum Rite and Kyrie XI in the Vatican Editions.