In W 9/93
the board noted that the intermediate compounds were known, so that these products could not serve as a common inventive concept, and that a technical feature contained in the process claims was also known. The board pointed out that a technical feature which already formed part of the state of the art could not, by definition, make a contribution over the prior art and did not, therefore, qualify as a unifying element within the meaning of R. 13.1 PCT. The board observed that, according to R. 13.2 PCT, as in force from 1.7.1992, an international patent application may relate to a group of inventions if there was a "technical relationship" among those inventions involving one or more of the same or corresponding "special technical features", i.e. such technical features that defined a contribution which each of the claimed inventions made over the prior art. The board went on to say that R. 13.1 PCT did not simply require some link between a group of inventions claimed in an international patent application, but a common inventive concept. This meant that there must be either a common technical problem or at least, if there was more than one technical problem, there must be one single technical concept behind the solutions of these different problems. Neither of these conditions was, however, met in this case.