The Guidelines are addressed primarily to EPO staff but they might also be of assistance to the parties to the proceedings and patent practitioners. However, the Guidelines are neither part of the EPC nor part of Case Law. They are not legally binding but just EPO internal administrative instructions. For the ultimate authority on practice in the EPO, it is necessary to refer firstly to the European Patent Convention itself including the Implementing Regulations and the Rules relating to Fees, and secondly to the interpretation put upon the EPC by the Boards of Appeal and the Enlarged Board of Appeal.