Any amendment to the parts of a European patent application or of a European patent relating to the disclosure (the description, claims and drawings) is subject to the mandatory prohibition on extension laid down in Art. 123(2) EPC and can therefore, irrespective of the context of the amendment made, only be made within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from the whole of these documents as filed (G 3/89, OJ 1993, 117; G 11/91, OJ 1993, 125; G 2/10, OJ 2012, 376, referring to this test as "gold standard"; confirmed for disclosed disclaimers in G 1/16, OJ 2018, A70; for undisclosed disclaimers, see however chapter II.E.1.7.2 c)). After the amendment the skilled person may not be presented with new technical information (G 2/10).

As can be seen from the "gold standard", the assessment of the requirements of Art. 123(2) EPC is to be done from the standpoint of the skilled person (see section II.E.1.3.2 "Standpoint of the skilled person" below).

The subject-matter must be at least implicitly disclosed (T 860/00; see also G 2/10, OJ 2012, 376), see in this chapter II.E.1.3.3 "Implicit disclosure" below.

The boards have emphasised with regard to various tests developed for different cases of amendments that they are only meant to provide an indication of whether an amendment complies with Art. 123(2) EPC as interpreted according to the "gold standard". They may assist in determining the allowability of an amendment but do not take the place of the "gold standard" and should not lead to a different result. See e.g. T 2561/11, T 755/12, T 2095/12, T 2599/12, T 46/15, T 1472/15 and T 553/15 with regard to the "essentiality test", T 1471/10 and T 1791/12 with regard to "intermediate generalisation", and T 873/94, OJ 1997, 456, T 60/03 and T 150/07 with regard to the "novelty test"; note however that special criteria apply for undisclosed disclaimers; for more details on these tests, see chapter II.E.1.4.4 "The essentiality or three-point test", chapter II.E.1.9. "Intermediate generalisations", chapter II.E.1.3.7 "Novelty test" and chapter II.E.1.7. "Disclaimers".