Liber Diurnus Romanorum Pontificum

Liber Diurnus Romanorum Pontificum (Latin for "Journal of the Roman Pontiffs") is the name given to a miscellaneous collection of ecclesiastical formulae used in the Papal chancery until about the 11th century. It fell into disuse through the changed circumstances of the times and was soon forgotten and lost.

The collection contains models of the important official documents usually prepared by the chancery; particularly of letters and official documents in connexion with the death, the election, and the consecration of the pope; the installation of newly elected bishops, especially of the suburbicarian bishops; also models for the profession of faith, the conferring of the pallium on archbishops, for the granting of privileges and dispensations, the founding of monasteries, the confirmation of acts by which the Church acquired property, the establishment of private chapels, and in general for all the many decrees called for by the extensive papal administration. The collection opens with the superscriptions and closing formulae used in writing to the Emperor and Empress at Constantinople, the Patricius, the Exarch and the Bishop of Ravenna, to a king, a consul, to patriarchs, metropolitans, priests and other clerics. The collection is important both for the history of law and for Church history, particularly for the history of the Roman Church. The formularies and models set down are taken from earlier papal documents, especially those of Gelasius I (492-496) and Gregory I (590-604).

This collection was certainly compiled in the chancery of the Roman Church, but probably only a comparatively small number of the formularies contained in the extant manuscripts were included at first, the remainder being added from time to time. There is no systematic arrangement of the formularies in the manuscripts.

Of the three existing manuscripts, the codex discovered in 1646 in the library of the monastery of Santa Croce in Gerusalemme in Rome and that since the eighteenth century is in the Vatican Archives, seems to date from the end of the eighth or the beginning of the ninth century; the manuscript, once in the Jesuit library at Clermont, France, now in the Benedictine library at Egmont, Netherlands, from the middle of the ninth century; and the third, originally from Bobbio, in the Ambrosian Library at Milan), to the end of the ninth or the beginning of the tenth century.

...
Wikipedia