"Guillelmus Guimondi filius jure hereditario patris mei", with the consent of "presulis Michaelis Abrincatensis...canonicorum...Erneisi de Verduno...", donated "decimam de Luot..." to Mont-Saint-Michel by charter dated "MLX--VI residente Michaele episcopo sede pontificali...et Rannulfo abbate in ecclesia sancti Michaelis", subscribed by "Guillelmi, Mathildis uxoris eius, Bertranni de Verduno...". Bertram de Verdun dates this charter to [1070/84], noting that Michel was bishop of Avranches from 1070 to 1094 and Ranulf de Bayeux abbé de Saint-Michel from 1063 to 1084.
Orderic Vitalis records the death of "Guillelmus de Abrincis filius Witmundi", dated to 1087 from the context. 1
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