According to the established case law of the boards of appeal, features which do not contribute to the solution of the problem set in the description are not to be considered in assessing the inventive step of a combination of features (T 37/82, OJ 1984, 71). According to this decision, in assessing the inventive step of a combination of features, consideration had to be given to a feature only if the applicant had provided evidence that it contributed, either independently or in conjunction with one or more of the other features, to the solution of the problem set in the description (see also T 65/87, T 144/90, T 206/91, T 574/92, T 226/94, T 912/94, T 15/97, T 471/98, T 442/02). Therefore, only those claimed features are to be considered which contribute causally to the solution of the problem (T 285/91). In T 294/89 the board stated that the additional feature provided no surprising advantage and did not make any contribution to solving the problem indicated. Hence, the said additional feature was not relevant for assessing the inventive step of the combination of features claimed.
In T 589/95 the terms of the solution of the technical problem extended into an area of use where it had been admitted that the relevant problem was known not to arise in practice. The board stated that, for such an area, the features of the solution did not contribute to the solution of the technical problem and could not be taken into account in the assessment of inventive step.
With reference to T 119/82, Board 3.3.05 held in T 72/95, T 157/97, T 176/97 and T 158/97 that similar considerations applied to technically non-functional modifications. An inventive step could not be claimed on the basis of a non-functional modification of a known device. If a known device was modified by adding a feature which had no technical function, this modification could not be inventive (see also above under point 9.1. "Treatment of technical and non-technical features").