Following
T 57/84, it was stated in
T 254/86 (OJ 1989, 115) that an invention which relied on a substantial and surprising improvement of a particular property did not also need to show advantages over the prior art with regard to other properties relevant to its use, provided the latter were maintained at a reasonable level so that the improvement was not completely offset by disadvantages in other respects to an unacceptable degree or in a manner which contradicted the disclosure of the invention fundamentally (see also
T 155/85, OJ 1988, 87). It was thus not necessary for there to be an improvement in every respect (
T 302/87,
T 470/90).