カール大帝の長男傴僂のピピン（英語版）を生んだヒミルトルードは、大帝の妾あるいは内妻であり、正式な妃ではなかった。Riche, Pierre, The Carolingians, p.86 ("Although he already had a son by his concubine, Himiltrude..."); Chamberlin, Russell, The Emperor Charlemagne, p.61: "he made the first of those confusing sexual relationships which was something more than concubinage, less than marriage...the Franks called it friedelehe, and it could perhaps be compared with the English system of common-law wife or husband..."
