Murals painted over each other present special problems of conservation. In Hungary 2-3 fragmentary layers are not unusual. If the upper layer is relatively intact it is completed and the older one not uncovered. Several fragmentary layers pose special problems. Mediaeval frescoes were discovered in the 19th century in Hungary, all covered with mortar. Then restoration in style was the predominant trend. Scientific restoration, based on Italian results began in the mid thirties. An important result of this was preservative restoration and distinguishable completions. A new trend, based on the given state of the work became accepted in the sixties. See also 16-194. -- AATA