1. A definition of a group of compounds in a claim by both structural and functional features is generally acceptable under Article 83 EPC as long as the skilled person is able to identify, without undue burden, those compounds out of the host of compounds defined by the structural feature(s) in the claim which also fulfil the claimed functional requirement(s).

In the present case, claim 1 of all requests is nothing more than an invitation to perform a research programme to identify suitable iridium complexes (other than those specifically disclosed in the patent) by trial and error. This amounts to an undue burden, such that the invention underlying claim 1 is insufficiently disclosed (points 4.2 to 4.9 of the Reasons, T 435/91 and T 1063/06 followed).

2. As regards the discretionary decision of an opposition division not to admit a late-filed document, a bare assertion of lack of prima facie relevance is not by itself sufficient reasoning.

Without any sufficient reasons being given by the opposition division for not admitting a late-filed document, the board is not in a position to decide whether or not the opposition division has exercised its discretion in an appropriate way. In such a situation, it is first necessary for the board to put itself in the place of the opposition division and to decide whether or not it would have exercised such discretion in the same way as the opposition division did (points 2.2.4 and 2.2.5 of the Reasons).