1. Novelty

The claimed sensor is defined by reference to characteristics of its response when used in a measurement set-up. Since none of the determining aspects of the measurement set-up is defined in claim 1, the technical features of the claimed sensor which are responsible for providing the measurement referred to in the claim remain obscure.

Legal certainty requires that a claimed subject-matter cannot be regarded as novel over the prior art on the basis of an ambiguous feature. Hence, defining a functional feature of the claimed sensor under undefined operating conditions is not appropriate to provide any distinction of the claimed sensor over the prior art sensors (see points 1.2 and 1.3 of the Reasons)

2. Admittance of auxiliary requests

None of the patentee's auxiliary requests were admitted into the proceedings because the patentee, during the first-instance opposition proceedings, deliberately chose not to defend any single auxiliary request, even though it was aware of the fact that its main request had not been found allowable by the opposition division (see points 2 and 3 of the Reasons).