According to the case law of the boards of appeal an examining division need not carry out an additional search if the technical features of the claims are notoriously well known. In particular, it is possible to raise an objection of lack of inventive step without documented prior art (see e.g. T 939/92, point 2.3 of the Reasons, OJ 1996, 309; T 1242/04, OJ 2007, 421, T 1411/08). That should be allowable where the objection was based on "notorious knowledge" or indisputably forms part of the common general knowledge. In such cases it would be inappropriate to carry out an additional search for documented prior art on purely formal grounds (T 1242/04, OJ 2007, 421; see also T 690/06, T 698/11).