The central industrial property office of a Contracting State must apply the procedure for the grant of a national patent or another protective right provided for by the legislation of this State at the request of the applicant for or the proprietor of the European patent under the circumstances specified in Art. 135(1). If the request for conversion is not filed within the three-month period specified in Art. 135(2), the effect referred to in Art. 66 will lapse.

The request for conversion is to be made to the EPO, except where the application is deemed withdrawn pursuant to Art. 77(5); in this case the request is filed with the central industrial property office with which the application was filed.

If a request for conversion is filed with the EPO, it must specify the Contracting States in which the application of national procedures is desired and be accompanied by a conversion fee. In the absence of the fee the applicant or proprietor is notified that the request will not be deemed to be filed until the fee is paid. The EPO transmits the request to the central industrial property offices of the specified Contracting States accompanied by a copy of the files relating to the European application or patent.