4. Transfer of the European patent 

Rule 22 applies mutatis mutandis to the registration of a transfer of the European patent during the opposition period or during opposition proceedings. After expiry of the opposition period or termination of the opposition proceedings, transfers are to be registered in the respective registers by the relevant national authorities and in the Unitary Patent Register. Where a fee is due and the request relates to both a European patent and to a European patent with unitary effect, only one fee is due (see UP Guidelines, 6.2).