The Novellae Constitutiones ("new constitutions"; , ), or Justinian's Novels, are now considered one of the four major units of Roman law initiated by Roman Emperor Justinian I in the course of his long reign (AD 527–565). The other three pieces are: the Codex Justinianus, the Digest, and the Institutes. Justinian's quaestor Tribonian was primarily responsible for compiling these last three. Together, the four parts are known as the Corpus Juris Civilis. Whereas the Code, Digest, and Institutes were designed by Justinian as coherent works, the Novels are diverse laws enacted after 534 (when he promulgated the second edition of the Code) that never were officially compiled during his reign. (According to Black's Law Dictionary, a translated, unabridged collection of Justinian's Greek Novels is known as Liber Authenticorum.)