The authors offer a new interpretation of the Kalisz rota (court records nos. 979 and 980) of 1422, which differs from the interpretation provided by the editors of 'Roty wielkopolskie' (Wielkopolska court records), H. Kowalewicz and W. Kuraszkiewicz. A detailed and penetrating analysis into the language and legal aspects of the rota shows that the interpretation of H. Kowalewicz and W. Kuraszkiewicz is untenable. The authors present ample support for the interpretation they put forward. The analysis bears on the methodological foundations of lexicographic research on Old Polish.