Arras, BM, 723
From Clavis Canonum
A copy of Regino of Prüm, Libri duo de synodalibus causis et disciplinis ecclesiasticis. According to Linda Fowler-Magerl, this manuscript contained the first version of the collection.
Certain sections of specific folios are available online at https://bvmm.irht.cnrs.fr/iiif/25979/canvas/canvas-2682851/view