In decision T1620/23, the Board of Appeal of the European Patent Office (EPO) dealt with the interpretation of patent claims in relation to decision G1/24.

The Board of Appeal overturned the decision of the Opposition Division concerning European patent application 18730654.3 entitled "Wheel hub, system comprising a brake disc and a wheel hub, and method for mounting a brake disc on a wheel hub" (translated from original German version). As a result, the patent was ultimately upheld as granted.

The decisive factor in the assessment was – apparently in addition to the lack of timely substantiation of attacks regarding inventive step – an interpretation of the feature "diameter" in the light of the description and drawings (G1/24).

Claim 1 (with a focus on feature 1.5) is helpful for understanding this:

1.1 - Wheel hub (1) comprising

1.2a - an outer collar region (12) viewed in the radial direction, and

1.2b - an inner core region (11) as viewed in the radial direction,

1.3 - wherein the inner core region (11) has a greater extension in the axial direction than the outer collar region (12), and

1.4 - wherein the wheel hub (1) has a primary recess (21) in the inner core region (11) that runs essentially axially for connecting a brake disc (2), characterized in that

1.5 a ratio between a radial distance (A1) between a rotational axis (A) and the primary recess (21) and a diameter (D) of the wheel hub (1) measured in the radial direction has a value between 0.6 and 0.3.

The opponent argued that, in feature 1.5, the ratio described with regard to the term "diameter" does not make sense, at least for the range between 0.5 and 0.6.

At this point (see section 1.2.4), decision G1/24 comes into play. On the one hand, because the use of the term "diameter" in feature M1.5 is contrary to the understanding of the skilled person. On the other hand, because the description and drawings must always be taken into account when assessing the patentability of the invention for the purpose of interpreting the patent claims (see headnote of G1/24).

According to the description and with reference to the drawings, the Board of Appeal considers that, contrary to the actual literal meaning, "diameter D" is to be understood as "radius." In order to resolve the above contradiction, the Board of Appeal considers that the skilled person must assume that the term "diameter" in the contested patent refers to "radius."

According to this interpretation, claim 1 in the granted version is therefore novel.

Overall, decision G1/24 seems to lead to the conclusion that even a supposedly fixed term such as "diameter" can be defined completely differently in light of the description and drawings. In the present case, this circumstance had a positive outcome for the patent proprietor.