The lexicon pertaining to Brother Berthold's »Rechtssumme« is an integral part of the overall edition. Its function is to provide a dictionary of definitions based on the three versions of the work. The references for the individual lemmas take the form of contextual references. Equivalents for the lemmas are also provided to the extent that they are identifiable in Berthold's source text, the »Summa confessorum« by Johannes von Freiburg. The lexicon also includes a glossary of equivalences and indexes of proper names and the Latin terms employed in Berthold's text.