A central time-limited opposition procedure and central limitation and revocation procedures before the EPO are available however. The opposition procedure allows any person except for the patent proprietor to oppose a granted European patent in an attempt to have the EPO revoke or amend the patent. The opposition procedure may only be initiated within nine months of the grant of the European patent. The limitation and revocation procedures allow the patentee to centrally request the limitation or revocation of their own European patent.