Under Art. 105 EPC, to intervene admissibly in opposition proceedings a party must show either that proceedings for infringement of the same patent have been instituted against him, or that following a request of the proprietor of the patent to cease alleged infringement, the third party has instituted proceedings for a ruling that he is not infringing the patent. Under Art. 105(2) EPC, an admissible intervention shall be treated as an opposition.