A compilation of legal rules and statutes. The earliest digests were systematic, comprehensive treatises on Roman law, composed by classical Roman jurists. Medieval copies of these Roman digests were sometimes glossed and illuminated, either with scenes related to the text or of an extraneous and often amusing character. In December 530, the Byzantine Emperor Justinian ordered a team led by Tribonian to compile a collection of excerpts from the classical jurists. The resultant work was called the Digest (or Pandects). The Digest, which formed part of the larger Code of Justinian, was arranged in fifty books and subdivided by titles. During the Middle Ages, it was commonly divided into the Digestum vetus (books I-XXXIV, 2), the Infortiatum (books XXIV, 2-XXXVIII), and the Digestum novum (books XXXIX-L).