 In a charter issued at Regensburg, he called him "regal son" ("filius regalis"), a term similar to "the king's son" ("filius regis"), which was the standard title of a legitimate royal son.This policy had supporters, like Abbot Regino of Prüm and the monks of Saint Gall, but also detractors, who appealed to Carloman's brother Louis.In early 879, Carloman was incapacitated by illness, perhaps a stroke.