The content of a European patent application or patent may be amended within the limits laid down in Art. 123(2) and Art. 123(3). (For the conditions governing amendments, see also A‑V, 2, H‑II, H‑IV, H‑V, and D‑V, 6.) This will normally be done by submitting missing documents or by filing replacement pages. Where replacement pages are filed, the applicant or patent proprietor is advised, in the interests of procedural efficiency, to identify clearly all amendments made, and indicate on which passages of the original application these amendments are based. Where whole paragraphs have been added or deleted, it is not necessary to renumber the paragraphs throughout the entire application or patent.

If handwritten amendments are filed during oral proceedings in opposition, the proprietor is invited in a Rule 82(2) communication to submit replacement paragraphs and/or claims only, and not replacement pages (see E‑III, 8.7.3, and OJ EPO 2016, A22, points 8 to 14).

Amendments should preferably be identified using functions available in a text editor to clearly indicate deletions and insertions in the amended text. Pages with such indications should be submitted in addition to clean copies. Alternatively, handwritten form is appropriate to fulfil the requirements of Rule 137(4), provided that clean copies are free from handwritten amendments.

The basis for amendments should preferably be indicated by including in the letter of reply a list of the amendments made and the precise basis for amendments in the application as filed (see H‑III, 2.1). Where the basis is not explicit, e.g. where a different wording is used or features are taken only from drawings or generalised from a specific embodiment, it is advisable to give a short explanation of why Art. 123(2) is fulfilled.