This chapter concerns the allowability of amendments under Art. 123(2) and (3) EPC, as well as corrections of errors in the parts of a patent application or of a patent relating to the disclosure (the description, claims and drawings) under R. 139 EPC. Other aspects related to amendments are dealt with elsewhere; see for example Chapters II.F. "Divisional applications"; II.D.3.1.2 "Priority"; IV.B.1.1, IV.B.2.5, IV.B.3.3, IV.B.3.4, IV.B.3.6, IV.B.3.7, IV.B.5 for the admissibility of amendments during the "Examination procedure"; IV.D.4 "Opposition procedure"; IV.E.4 "Appeal procedure"; III.I. "Main and auxiliary requests". Part H of the Guidelines for Examination in the European Patent Office gives an overall picture of the various principles applicable to amendments (formal admissibility and substantive allowability).