The fifteenth-century manuscript Suppl. Gr. 45 (Austrian National Library, ÖNB, Vienna) contains an extensive Greek-Latin dictionary, where one can find a great number of marginal notes written by different hands and in different languages (Greek, Latin and Italian). Approximately sixty of these glossary notes are quotations from the well-known Byzantine code of law, the Basilika (9th century), which was initiated by Emperor Basil I and completed under the reign of his successor, Leo VI the Wise. In my paper, I intend to examine these marginal notes and argue that their direct source text is not the monumental code of law, the Basilika itself, but rather its abridged version from the 10th cent., the SynopsisMaior Basilicorum.