 In the medieval period, the abbess exercised the functions of a bishop, except for the sacramental ones, and those of a ruler, over the very extensive estates of the abbey, and had no clerical superior except the pope.Because of its advancement by the Liudolfings (the family of the Ottonian Emperors) the abbey became "reichsunmittelbar" (an Imperial abbey) sometime between 874 and 947.Its best years began in 973 under the Abbess Mathilde, granddaughter of Otto I and thus herself a Liudolfing, who governed the abbey until 1011.