Each of the 445 alphabetized "regulae," or commonly accepted legal principles, is followed by a list of exceptions (fallentiae) that may invalidate it.
Title page in red and black.
Device of Nicolas Petit (two-faced person with in her hands a shining head and a clock; in backround, a corpse; with initials "N P" and motto "Cogita ante opus fine[m]") on t.p. and on last verso.
Caption, fo. clxviij: Incipit Tractatus vtilissimus super materia permutationum domini Federici de Senis ...
Caption, fo. clxxx: Repetitio l[egis] Apertissimi iuris ... Jacobus Molinaris ... (lecture on Codex 3:1:16)
Colophon: Excudebat Lugduni Petrus Luccius Princeps expensis Nicolai Parui, anno a Christo nato M.cccccxl.
Signatures: aa-bb⁸ a-z⁸.
Includes index.