European patent applications may be filed in any language, in accordance with Article 5 of the Patent Law Treaty (PLT). However, if an application is filed in a language other than one of the three official languages, namely English, French and German, a translation must be filed into one of the official languages within two months from the date of filing. The official language of filing (or of the translation) becomes the "language of proceedings" and is used by the EPO for communications.