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 meet the requirements for being admitted into the proceedings (see H‑II, H‑III).
Secondly, amendments must be allowable, which means, in particular, that they must not:
(i)add to the application or patent subject-matter which was not disclosed in the application as originally filed (Art. 123(2))
(ii)introduce other deficiencies (such as lack of clarity in the claims – Art. 84)
(iii)extend the protection conferred by a granted patent (Art. 123(3)).