The principle of the protection of legitimate expectations is a general principle well established in European Community law and generally recognised in the EPC contracting states and board of appeal case law (G 2/97, OJ 1999, 123; see also R 4/09). Its application to procedures before the EPO implies that measures taken by the EPO should not violate the reasonable expectations of parties to such proceedings (G 5/88, G 7/88, G 8/88, OJ 1991, 137). The term "good faith" is also used to describe this concept (J 10/84, OJ 1985, 71; J 38/97). Users of the European patent system, who are parties in proceedings before the EPO, must also act in good faith (G 2/97, R 4/09). An alleged violation of the principle of the protection of legitimate expectations is in itself not a ground for a petition for review under Art. 112a EPC (R 13/11).