The Codex Carolinus is a collection of the epistles of the popes to Charles Martel, (whom they style Subregulus), Pepin, and Charlemagne, as far as the year 791, when it was formed by the last of these princes. His original and authentic Ms. (Bibliothecae Cubicularis) is now in the Imperial library of Vienna, and has been published by Lambecius and Muratori, (Script. Rerum Ital. tom. iii. pars ii. p. 75, etc.)