But from time to time the Church hierarchy, and some popes, have given opinions on various matters; although these guidelines are not binding, they are often followed.[41] Pope Pius XII stated that women should cover their upper arms and shoulders, that their skirts should cover at least as far as the knee, and the neckline should not reveal anything.[42] Giuseppe Cardinal Siri of Genoa stated that trousers were unacceptable dress for women.[43] Many traditional Catholics have attempted to further expand on this latter standard.[44]