e) Construction with regard to all technically logical interpretations 

In T 1408/04 the board held that while the claims had to be interpreted by a "mind willing to understand" and not by "a mind desirous of misunderstanding", this was understood to mean only that technically illogical interpretations should be excluded (see T 190/99). The terms to be interpreted had a wider technical interpretation than envisaged by the appellant. A "mind willing to understand" did not require that a broad term needed to be interpreted more narrowly (even if the narrow interpretation referred to a structure which was very common, but not exclusive, in the technical field concerned), but instead that a broad term should be interpreted with regard to all technically logical interpretations thereof. Based on this understanding of the limiting terms introduced into the claim the board came to the conclusion that the amendment to claim 1 as granted resulted in an intermediate generalisation.

In T 1791/16 the board held that, in the interest of legal certainty, all technically reasonable interpretations of an ambiguous claim had to be considered. If one of those interpretations contained matter that extended beyond the content of the application as originally filed, it had to be concluded that there was added subject-matter (followed e.g. in T 945/20 and T 193/22). This approach was recently followed in T 405/24, T 1394/23, T 1973/23 and T 837/24. In T 837/24 the board stated that a claim had to be interpreted according to the technical information it provided. All interpretations that were technically valid had to be considered as technically meaningful. None of these interpretations could extend beyond the content of the application as filed within the meaning of Art. 123(2) EPC. There was no indication in Art. 69(1) EPC or in G 1/24 that "using", "consulting" or "referring to" the description and drawings would require a claim interpretation that necessarily complied with Art. 123(2) EPC, irrespective of whether that interpretation was preferable or more likely. Likewise, in T 1973/23 the board explained that G 1/24 could not be relied upon to adopt a narrow interpretation of the claim based on the description solely to ensure compliance with Art. 123(2) EPC.

A different approach was taken in T 1345/23 and T 1886/22, both citing T 367/20. According to T 367/20, which discussed two mutually exclusive interpretations of a claim feature, the first step was to interpret the amended claimed subject-matter from the perspective of the skilled person. Whether this subject-matter had been originally disclosed had to be assessed in a second step. In other words, the claim interpretation adopted by the deciding body defined the subject-matter which had to be disclosed in the application as filed. The board stressed that a claim feature did not have to be interpreted in isolation but in the context of the whole document it formed part of. This context included the other features in the claims as well as the description and the drawings. After G 1/24 was issued, see T 2048/22 and T 727/23. In T 873/23, endorsed in T 981/23, the board considered that, also in the context of Art. 123(2) EPC and not only regarding "patentability of an invention under Articles 52 to 57" (G 1/24), the claims were the starting point and the basis for the assessment and that the description and that drawings must always be consulted to interpret the claims. This was, however, to be done by taking due account of the primacy of the claims (T 1473/19).

In T 325/23 the board held that all technically reasonable interpretations of an ambiguous claim had to be considered when assessing Art. 123(2) EPC. The board agreed with the appellant (patent proprietor) that in general there exists no file wrapper estoppel in proceedings under the EPC. However, the fact that the appellant had argued during the prosecution of the patent application that the limitation "single row" added to claim 1 was made in order to limit the subject-matter of claim 1 against prior-art document D9 which disclosed "multiple rows", could be taken as an indication that a narrow interpretation of the term "single row" was at least not technically unreasonable. The consideration of such events in the file history was used to determine whether an interpretation was technically reasonable or not, without excluding other interpretations.