T 2318/22 06-02-2025

1. Main request - content of the divisional application (Article 76(1) EPC)

1.1 A European divisional application may be filed only in respect of subject-matter which does not extend beyond the content of the earlier application as filed (Article 76(1), second sentence, EPC).

In the case of a sequence of applications consisting of a root application followed by divisional applications, each divided from its predecessor, it is a necessary and sufficient condition for a divisional application of that sequence to comply with Article 76(1), second sentence, EPC that anything disclosed in that divisional application be directly and unambiguously derivable from what is disclosed in each of the preceding applications as filed (see Case Law of the Boards of Appeal of the European Patent Office, 10th edition, 2022, II.F.2.1.2).

1.2 The opponent argued that claim 1 of the main request did not meet the requirements of Article 76(1) EPC because feature (b) specified that the first-type syntax elements were interspersed with the second-type syntax elements (see section 10.1 of the opponent's statement of grounds of appeal). However, the basis indicated by the patent proprietor on page 17, lines 11 to 14 of the great-grandparent application disclosed second-type syntax elements being interspersed with first-type syntax elements. Claim 3 of the great-grandparent application specified that second-type syntax elements were between first-type syntax elements. Hence, while the description and claim 3 disclosed second-type syntax elements located between first-type syntax elements, claim 1 of the main request specified the other way round.

The opponent also argued that claim 1 did not specify any particular temporal order between first-type and second-type syntax elements and that, therefore, it did not exclude the second-type syntax element being located before the first-type syntax element in the data stream. Coding the first-type syntax element after the second-type syntax element was technically sensible, even if this might be redundant in some circumstances.

Further, claim 1 did not require that the second-type syntax element be coded only when the first-type syntax element indicated that a significant transform coefficient was coded. The term "interspersed" did not imply that the second-type syntax element was coded only on condition that a significant coefficient was present at the respective position. And nor was this implied by the definition of the second-type syntax element in claim 1.

In addition, claim 9 of the great-grandparent application could not serve as a basis because it did not specify coding the second-type syntax element.

1.3 The patent proprietor argued that interspersing syntax elements of one type with syntax elements of another type resulted only in an alternating sequence of the two types and that it thus made no difference whether first-type syntax elements were interspersed with second-type syntax elements or vice versa (see section I.1(h) of the patent proprietor's letter of 22 May 2023).

Moreover, the wording of claim 1 included an implicit order. Indicating whether a transform coefficient was "the last significant transform coefficient" in the transform coefficient block implied that, at the time of decoding the second-type syntax element, the decoder already knew that the transform coefficient at the respective position was significant, i.e. that the respective first-type syntax element had been signalled in the data stream. Thus, the semantics of the expression "second-type syntax elements" in claim 1 implied that the respective first-type syntax elements were extracted prior to the second-type syntax elements (see section 2.1 of the patent proprietor's letter of 16 December 2024). The definition of the second-type syntax element in claim 1 would not make technical sense if this element were to be extracted from the data stream for positions in the transform coefficient block at which there was no significant coefficient.

Further, if the second-type syntax elements were to be sent before the first-type syntax elements, it would be nonsensical to signal the first-type syntax element for the position at which the last significant coefficient in the transform coefficient block was coded.

In addition, claim 9 of the great-grandparent application did not include any interspersing.

1.4 Page 17, lines 11 to 14 of the description of the great-grandparent application, which the patent proprietor indicated as a basis, discloses coding syntax elements last_significant_coeff_flag (second-type syntax elements) interspersed with the sequence of significant_coeff_flag (first-type syntax elements) at the positions where the first-type syntax element signals a significant coefficient.

It is apparent from page 17, lines 11 to 21 of the description of the great-grandparent application that it is only when the first-type syntax element signals that a significant transform coefficient is present at a scanning position that the second-type syntax element for this position is coded, i.e. is present in the data stream. The presence of an interspersed second-type syntax element in the data stream at a scanning position is conditional on an immediately preceding first-type syntax element signalling the presence of a significant transform coefficient at the scanning position.

Claim 3 of the great-grandparent application indicates that the second-type syntax elements follow the first-type syntax elements in so far as it specifies "extract, between first-type syntax elements indicating that at the respective associated position a significant transform coefficient is situated, and immediately subsequent first-type syntax elements, second-type syntax elements ... for the associated positions at which a significant transform coefficient is situated".

1.5 The board agrees with the opponent that the definition of the second-type syntax element in claim 1 does not imply any particular temporal order or conditional coding. The second-type syntax element only indicates "whether a transform coefficient at the associated position is the last significant transform coefficient". It is not apparent from this wording that a first-type syntax element indicating whether a significant coefficient is present at the associated position must precede the second-type syntax element.

The patent proprietor's argument that coding the second-type syntax element before the first-type syntax element would not make technical sense is not convincing. Coding the second-type syntax element before the first-type syntax element may generate redundant information or be less efficient than coding the first-type syntax element first and coding the second-type syntax element only when the first-type syntax element indicates a significant coefficient at the corresponding position. However, an inferior coding efficiency or generating redundant data are not necessarily suitable criteria for judging whether an implementation makes technical sense. Irrespective of the order in which the elements are signalled and whether the second-type syntax element is only conditionally coded, the information conveyed by the first-type and second-type syntax elements is coded in the data stream and available to the decoder. Therefore, reading feature (b) in such a way that the first-type syntax element is included before the second-type syntax element in the data stream does not reflect the only technically sensible way of reading this feature.

1.6 Claim 1 thus encompasses second-type syntax elements preceding corresponding first-type syntax elements in the data stream. However, the great-grandparent application does not provide a direct and unambiguous basis for this order (see point 1.4 above).

1.7 In view of the above, claim 1 of the main request does not meet the requirements of Article 76(1) EPC.

2. Auxiliary requests I to V - content of the divisional application (Article 76(1) EPC)

2.1 Claim 1 of auxiliary requests I to V specifies feature (b) in the same way as claim 1 of the main request.

2.2 Neither the patent proprietor nor the opponent submitted further comments.

2.3 Consequently, for the same reasons as set out with respect to the main request, claim 1 of auxiliary requests I to V does not meet the requirements of Article 76(1) EPC.

3. Auxiliary request VI - admittance (Article 13(2) RPBA)

3.1 The claims of auxiliary request VI were filed with a letter dated 16 December 2024, i.e. after the board's communication under Article 15(1) RPBA, and are therefore amendments within the meaning of Article 13(2) RPBA.

3.2 Under Article 13(2) RPBA, any amendment to a party's appeal case after notification of a communication under Article 15(1) RPBA is, in principle, not to be taken into account unless there are exceptional circumstances which have been justified with cogent reasons by the party concerned.

The explanatory remarks on Article 13(2) RPBA contain the following guidance: "The basic principle of the third level of the convergent approach is that, at this stage of the appeal proceedings, amendments to a party's appeal case are not to be taken into consideration. However, a limited exception is provided for: it requires a party to present compelling reasons which justify clearly why the circumstances leading to the amendment are indeed exceptional in the particular appeal ('cogent reasons'). For example, if a party submits that the Board raised an objection for the first time in a communication, it must explain precisely why this objection is new and does not fall under objections previously raised by the Board or a party. The Board may decide to admit the amendment in the exercise of its discretion" (see Supplementary publication 2, OJ EPO 2020, explanatory remarks on Article 13(2), page 60, third paragraph).

3.3 The patent proprietor submitted that the amendments to claim 1 of auxiliary request VI had been filed in response to, and addressed, the objection under Article 76(1) EPC raised for the first time in point 2.5 of the board's communication under Article 15(1) RPBA and relating to the first-type syntax elements being interspersed with the second-type syntax elements. This situation constituted exceptional circumstances within the meaning of Article 13(2) RPBA.

The patent proprietor argued that the opponent's objection under Article 76(1) EPC was based on the order of elements in the claimed feature "wherein the first-type syntax elements are interspersed with the second-type syntax element" differing from the order of elements in the phrase "the significance map coding involves a coding of binary syntax elements last_significant_coeff_ flag [second-type syntax elements] interspersed with the sequence of significant_coeff_ flag [first-type syntax elements] at the positions thereof" in the great-grandparent application. In contrast, the board had reasoned that the phrase "interspersed with" per se did not imply any particular order of the elements but that the great-grandparent application did not provide a basis for any of the orders of the elements specified in claim 1.

Moreover, the opponent's objection was not substantiated. The discussion of claim 3 of the great-grandparent application on page 14 of the opponent's statement of grounds of appeal did not suffice to substantiate the objection, and the submissions on page 53 of the opponent's statement of grounds of appeal related to a different objection from that raised by the board in point 2.5 of its communication under Article 15(1) RPBA.

Further, the patent proprietor stated that, in view of the large number of objections, it was not appropriate for it to file requests addressing them all, in particular if they were not substantiated.

3.4 The opponent submitted that the objection was raised and substantiated in point 7.1 of the notice of opposition and on pages 14 and 53 of the statement of grounds of appeal. With reference to the description (page 17, lines 11 to 14) and claim 3 of the great-grandparent application, it had disputed, from the outset of the opposition proceedings, the existence of a basis in the great-grandparent application for interspersing the first-type syntax elements with the second-type syntax elements.

Further, the fact that a board arrives at a different conclusion from the opposition division could not be considered an exceptional circumstance within the meaning of Article 13(2) RPBA.

3.5 The board finds that the comments in point 2.5 of its communication under Article 15(1) RPBA are a natural development of the case which takes account of the arguments of both parties and which is not to be considered exceptional within the meaning of Article 13(2) RPBA.

3.5.1 In the statement of grounds of appeal (see section 10.1), the opponent referred to page 17, lines 11 to 14 of the description, which the patent proprietor had indicated as a basis for the contested feature, and to claim 3 of the great-grandparent application. It submitted that said passage and claim 3 of the great-grandparent application disclosed the inverse order of elements.

The board considers that, in the present case, the identification of the claimed feature which allegedly infringed the requirements of Article 76(1) EPC and the explanation as to why the feature was not directly and unambiguously derivable from the basis indicated by the patent proprietor constitute sufficient substantiation of the objection.

3.5.2 In point 2.5 of its communication under Article 15(1) RPBA, the board concurred with the opponent that the great-grandparent application did not provide a basis for second-type syntax elements for a given position preceding first-type syntax elements for that position. This conclusion was based on page 17, lines 11 to 21 of the description and claim 3 of the great-grandparent application. The passage of the description corresponds to the indicated basis for the contested feature and to a subsequent explanation of the interspersing described therein.

Therefore, the board relied on substantially the same facts and evidence as those submitted by the opponent.

3.5.3 The board finds that this normal development of a case, based on substantially the same factual and evidentiary framework, does not constitute exceptional circumstances within the meaning of Article 13(2) RPBA that would justify taking into account auxiliary request VI.

3.5.4 Moreover, the board's agreement with one of the opponent's arguments cannot be considered "exceptional circumstances". If exceptional circumstances were to be acknowledged whenever a board agrees with, and further develops, an objection raised by the opponent, the board would be unable to evaluate and comment on the arguments submitted by both parties to come to a balanced and reasoned conclusion without opening the door to the filing of new requests.

3.5.5 The objection was known to the patent proprietor from the outset of the appeal proceedings and this would have provided a sufficient reason for the filing of an amended auxiliary request by the patent proprietor at an early stage to overcome the objection. However, the patent proprietor decided to file such a request only after the board's communication under Article 15(1) RPBA. It is within the patent proprietor's sphere of risk to counter an objection only by way of arguments and to defer the filing of requests addressing the objection to a later stage of the appeal proceedings.

3.6 In view of the above, the board, exercising its discretion under Article 13(2) RPBA, decided not to take into account auxiliary request VI.

4. Auxiliary requests VII and VIII - admittance (Article 13(2) RPBA)

4.1 The claims of auxiliary requests VII and VIII were filed with a letter dated 16 December 2024, i.e. after the board's communication under Article 15(1) RPBA, and are therefore amendments within the meaning of Article 13(2) RPBA.

4.2 Neither the patent proprietor nor the opponent submitted further comments.

4.3 Consequently, for the same reasons as set out with respect to auxiliary request VI, the board, exercising its discretion under Article 13(2) RPBA, decided not to take into account auxiliary requests VII and VIII.

5. Auxiliary requests IX and X - content of the divisional application (Article 76(1) EPC)

5.1 Claim 1 of auxiliary requests IX and X specifies feature (b) in the same way as claim 1 of the main request.

5.2 Neither the patent proprietor nor the opponent submitted further comments.

5.3 Consequently, for the same reasons as set out with respect to the main request, claim 1 of auxiliary requests IX and X does not meet the requirements of Article 76(1) EPC.

6. Request for suspension of the appeal proceedings

The patent proprietor's request for suspension of the appeal proceedings in view of pending referral G 1/24 was based on the question of how certain claimed features were to be interpreted. However, this question was not relevant to the present decision. Therefore, any possible outcome of pending referral G 1/24 has no impact on the case in hand. Consequently, the board finds that this request is no longer relevant.

7. Conclusion

Claim 1 of the main request and auxiliary requests I to V, IX and X does not meet the requirements of Article 76(1) EPC. Auxiliary requests VI to VIII were not taken into account under Article 13(2) RPBA. Since none of the patent proprietor's requests is allowable, the decision under appeal is to be set aside and the patent is to be revoked.