About 100 years after the Sachsenspiegel was created, the university-trained lawyer Johann von Buch, following the example of the Glossae Ordinariae of Roman canon law, provides the legal book with a gloss. This glossing, the so-called Buch’s gloss, has shaped the further development of Saxon law over centuries. Gesinde Güldemund examines the inheritance law of Buch’s glosses and uses the findings of their investigation for some general questions in gloss research. The focus is on the question of the legal content of Buch’s gloss, its relationship to the law of the Sachsenspiegel on the one hand and Roman canon law on the other.