A European patent application or European patent may be amended in examination, opposition and limitation proceedings. With regard to amendments filed in such proceedings, there are a number of important aspects to consider. Firstly, amendments must be admissible, i.e. they must be admitted into the procedure by the competent department of the EPO. Secondly, amendments must be allowable, which means that they must not:
Chapters H‑II and H‑III deal with the admissibility of amendments, while Chapters H‑IV and H‑V deal with their allowability. Chapter H‑VI is dedicated to the correction of evident errors in documents submitted to the EPO or in decisions of the Examining or Opposition Divisions.