4.2.1 The subject-matter to be excluded is not disclosed in the application as originally filed (so-called undisclosed disclaimers) 

Limiting the scope of a claim by using a "disclaimer" to exclude a technical feature not disclosed in the application as filed may be allowable under Art. 123(2) in the following cases (see G 1/03 and G 1/16 and F‑IV, 4.20):

(i)restoring novelty over a disclosure under Art. 54(3);

(ii)restoring novelty over an accidental anticipation under Art. 54(2). "An anticipation is accidental if it is so unrelated to and remote from the claimed invention that the person skilled in the art would never have taken it into consideration when making the invention". The status of "accidental" is to be ascertained without looking at the available further state of the art. A related document does not become an accidental anticipation merely because there are other disclosures even more closely related. The fact that a document is not considered to be the closest prior art is insufficient for achieving the status of "accidental". An accidental disclosure has nothing to do with the teaching of the claimed invention, since it is not relevant for examining inventive step. For example, this is the case when the same compounds serve as starting materials in entirely different reactions yielding different end products (see T 298/01). A prior art, the teaching of which leads away from the invention, however, does not constitute an accidental anticipation; the fact that the novelty destroying disclosure is a comparative example is also insufficient for achieving the status of "accidental" (see T 14/01 and T 1146/01);

(iii)removing subject-matter which, under Art. 52 to Art. 57, is excluded from patentability for non-technical reasons. For example, the insertion of "non-human" in order to satisfy the requirements of Art. 53(a) is allowable.

These criteria notwithstanding the introduction of the undisclosed disclaimer may not provide a technical contribution to the subject-matter disclosed in the application as filed. The undisclosed disclaimer (which inevitably quantitatively reduces the original technical teaching) may not qualitatively change the original technical teaching in the sense that the applicant's or patent proprietor's position with regard to other requirements for patentability is improved. In particular, it may not be or become relevant for the assessment of inventive step or for the question of sufficiency of disclosure. Hence, the evaluation of inventive step has to be carried out disregarding the undisclosed disclaimer (see G 1/16).

The disclaimer may not remove more than necessary either to restore novelty (cases (i) and (ii) above) or to disclaim subject-matter excluded from patentability for non-technical reasons (case (iii) above).

An undisclosed disclaimer is, in particular, not allowable if:

(i) it is made in order to exclude non-working embodiments or remedy insufficient disclosure;

(ii) it makes a technical contribution. 

(iii) the limitation is relevant for assessing inventive step; 

(iv) the disclaimer, which would otherwise be allowable on the basis of a conflicting application alone (Art. 54(3)), renders the invention novel or inventive over a separate prior art document under Art. 54(2), which is a not accidental anticipation of the claimed invention;

(v) the disclaimer based on a conflicting application also serves another purpose, e.g. it removes a deficiency under Art. 83.

Art. 84 applies equally to the claim per se and to the disclaimer itself (see T 2130/11).

In the interest of the patent's transparency, the excluded prior art must be indicated in the description in accordance with Rule 42(1)(b) and the relation between the prior art and the disclaimer must be shown.