What is "berengaudus"

Berengaudus (840–892) was a Benedictine monk, supposed author of Expositio super septem visiones libri Apocalypsis, a Latin commentary on the Book of Revelation. He has traditionally been assumed to be a monk of Ferrières Abbey, at the time of Lupus Servatus. The attribution has been questioned, but the Expositio was later (by the 12th century) much circulated in manuscript. It was printed in Patrologia Latina vol. XVII under Ambrose, following an attribution by Cuthbert Tunstall.