The Corpus iuris canonici is traditionally composed by: I. The collection of decreta compiled by Gratianus (Decretum Gratiani), and II. The decretales of the popes, divided into: 1⁰) the five books compiled at the order of Gregorius IX; 2⁰) the sixth book promulgated by Bonifatius VIII; 3⁰) the five books of constitutiones promulgated by Clemens V; 4⁰) the Extravagantes seu constitutiones viginti promulgated by Joannes XXII; 5⁰) The Extravagantes communes, a diversis Romanis pontificibus post Sextum editae. For practical purposes the Corpus was generally printed in three volumes: 1⁰) Decretum Gratiani; 2⁰) Decretales Gregorii IX; 3⁰) Sextus liber Bonifatii VIII, containing also the Constitutiones Clementis V, the Extravagantes Joannis XXII, and the Extravagantes communes. On the 16th century editions of the Corpus, with specific regard to Plantin's publications: C. de Clercq, 'Les éditions bibliques, liturgiques et canoniques de Plantin' in De Gulden Passer, 34, 1956, pages 182-188. See also C. de Clercq, 'Note sur quelques éditions du Corpus Iuris Canonici de 1547 à 1580' in Studia Gratiana, Bologna, 9, 1966, pages 145-152.