The Decretum Gratiani or Concordia discordantium canonum (in some manuscripts Concordantia discordantium canonum) is a collection of Canon law compiled and written in the twelfth century as a legal textbook by a jurist (perhaps) named Gratian. It forms the first part of the collection of six legal texts, which became known as the Corpus Juris Canonici and which retained legal force in the Roman Catholic Church up until Pentecost Sunday, May 27, 1917, when the a revised Code of Canon Law (Codex Juris canonici) was promulgated by Pope Benedict XV. (The Code became binding throughout the Western Church the Pentecost Sunday of the following year, 19 May 1918.)