character. Some of the 39 EPC Contracting States require the patentee to file a full translation of the granted European patent with the national patent office of the State if the text of the European patent as granted is not in one of their official languages. If the translation is not filed, the European patent is deemed to have no effect from the outset in that State. The London Agreement, which entered into force on May 1, 2008, significantly reduces the number of required translations in the states that are party to it. 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. After the unitary European examination and opposition phase ends, nearly all "unitary" nature of the European patent dissolves, and what remains is a collection of essentially-independent national patents, and ownership, validity and infringement of each being determined independently under respective national law. provides that, in each member country, the national part of the European patent has the identical effect as a national patent with the identical claims would have. The European Patent Convention expressly adopts national law for all substantive attributes of a national part of a European patent, with the following exceptions: standards for revocation - national law is expressly preempted, and grounds for revoking a national part are limited to five grounds specified in (subject matter, enabling disclosure, and claims beyond the content of the application as filed, protection has been extended or improper proprietor) - though each state is free to interpret the five grounds of Art. 138 under its own national law. infringement by the direct product of a patented process patent term, 20 years from the filing date. All other substantive attributes of each national part of an EP patent, such as what acts constitute infringement (indirect and divided infringement, infringement by equivalents, extraterritorial infringement, infringement outside the term of the patent with economic effect during the term of the patent, infringement of product claims by processes for making