T 0438/99 24-01-2002

1. The appeal is admissible.

2. A preliminary and potentially determinative issue to be decided in this appeal is the permissibility under Article 123(2) EPC of the amendment of the description of the application as originally filed by deletion of the reference to the use of the (111) crystallographic direction for determination of crystallite size by X-ray diffraction, an amendment which was effected in the examination procedure, objected to by the opponent in the notice of opposition and explicitly approved by the opposition division in the decision under appeal at point 2 of the reasons. A second and closely linked issue is the permissibility under Article 123(2) EPC of the proposed amendment of claim 1 in the present appeal proceedings by insertion of a reference to the (110) direction, an amendment which, by the same token, the opposition division indicated as one which the examining division "could also have allowed" as a correction of a typographical error under Rule 88, second sentence, EPC.

3. As regards this first issue, the Enlarged Board of Appeal in its decision G 11/91, Glu-Gln / Celtrix OJ EPO 1993, 125 explained the relationship between Article 123(2) EPC and Rule 88, second sentence, EPC, and summarised it as follows:

"1. The parts of a European patent application or of a European patent relating to the disclosure (the description, claims and drawings) may be corrected under Rule 88, second sentence, EPC only 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. Such a correction is of a strictly declaratory nature and thus does not infringe the prohibition of extension under Article 123(2) EPC.

2. Evidence of what was common general knowledge on the date of filing may be furnished in connection with an admissible request for correction in any suitable form."

3.1. In particular, at point 2 of the reasons, last two sentences, the Enlarged Board of Appeal specified a first precondition that a corrective amendment must meet: "The requirement laid down in Rule 88, second sentence, EPC that a correction must be obvious further implies that the incorrect information is objectively recognisable, too. The skilled person must thus be in a position objectively and unambiguously to recognise the incorrect information using common general knowledge." and again at point 5:

".. such an obvious error that a skilled person is in no doubt that this information is not correct and - considered objectively - cannot be meant to read as such. If, on the other hand, it is doubtful whether any information at all is incorrect, then a correction is ruled out. The same applies if incorrect information only becomes apparent in the light of the proposed correction."

3.2. In addition, at point 6 of the reasons, the Enlarged Board of Appeal specified a second precondition that a corrective amendment must meet:

"The parts of a European patent application as filed which relate to the disclosure must further allow a skilled person - using the common general knowledge on the date of filing - directly and unequivocally to ascertain the precise content of the information the person making the request actually meant to give, instead of the incorrect particulars, on the date of filing or when making an amendment under Article 123 EPC, so that, for said skilled person, "it is immediately evident that nothing else would have been intended than what is offered as the correction" (Rule 88, second sentence, EPC). However, if there is any doubt that nothing else would have been intended than what is offered as the correction, a correction cannot be made."

4. The board is persuaded of the plausibility of the respondent proprietor's submission that the person skilled in the art would appreciate that the reference in the description of the application as originally filed to measuring particle or crystallite size by X-ray diffraction along the (111) direction could not have been intended. The appellant opponent has not adduced any evidence that measurements are ever made on FeAl type bcc lattice powders along this direction, the document D5 showing only (110) and (200), while the document DP2 provides, in the judgement of the board, convincing evidence that the (111) peak is so much weaker than peaks for, eg (110) and (200), that it is simply not credible that the latter direction would ever be used, and certainly would not be taught in a patent application without comment.

4.1. For the avoidance of doubt which could be provoked by the board's conclusion on this first issue, three conceivable arguments in support of this conclusion which, on reflection, are not convincing should be mentioned for completeness. Firstly - as is implicit in the Enlarged Board of Appeal's reasoning quoted above - an argument that a skilled person who attempted to implement the literal teaching of the application would soon discover that it was virtually impossible to make measurements in the (111) direction because the peak was scarcely above the noise level, cannot be entertained, since it would represent an undue burden for the reader of the specification if he had to conduct experiments to interpret or construe the disclosure. Secondly the mere disparity between the value (111) in the description of the application as originally filed and the value (110) in the priority document does not of itself allow any conclusion to be drawn about the existence of an error in the application documents proper. Thirdly the mention of (110) in the priority document in this particular case was not in a context which could provide significant evidential support for an assertion that it was a matter of common general knowledge in the art that the value (111) could not be correct, although, as correctly pointed out by the respondent proprietor, it was in principle possible that a priority document could constitute or include evidence as to the common general knowledge in the art; cf G 11/91, reasons point 7 :

"documents other than the description, claims and drawings may only be used insofar as they are sufficient for proving the common general knowledge on the date of filing."

4.2. Hence the board concludes that the first precondition for the permissibility of a corrective amendment (cf 3.1 above) is fulfilled.

5. As regards the second precondition (point 3.2 above), however, ie that it should be immediately evident that nothing else would have been intended than what is offered as the correction, the board is not persuaded of the plausibility of the respondent proprietor's argument.

5.1. The "offered correction" now takes two alternative forms:

(i) replacement of the erroneous value (111) by the allegedly obviously correct value (110), which features in the respondent's main request or,

(ii) deletion without replacement of the erroneous value (111), which features in the other requests.

5.2. As regards the offered correction (110), the evidence of usable measurement peaks in DP2 serves, in the judgement of the board, to confirm the evidence in D5 that (110) is not the only plausible correction. D5 cites (differing) results for crystallite size based on (110) and (200) directions, while DP2 shows that whereas the (110) peak is the largest, other significant peaks occur, eg at (200) and (211). The respondent proprietor's argument that the fact that the most plausible value (110) differs in only one digit from the recognisably false value (111) would enable the person skilled in the art to resolve the ambiguity in favour of (110), is not convincing, since precisely in the disclosure of an invention the skilled person has to expect the unexpected. An inventive teaching necessarily departs from routine procedures at some point. Indeed it can be quite as plausibly argued that if the standard or most usual value (110) was to be used it would not, as a default value, need to be indicated, whereas the fact that a specific measurement direction is mentioned suggests that significant technical information was being imparted at this point. In this connection the board is mindful of the fact, evidenced by D5, that crystallite size is a parameter dependent on the measurement method employed, resulting in different "sizes" for measurements along different directions. In addition, the fact that the claimed powder is distinguished from prior art powders by a rather small difference in the crystallite size suggests that the precise measurement method used to determine this size could well be significant.

5.2.1. Hence the board concludes that the second precondition of being immediately evident that nothing else would have been intended than what is offered as the correction, is not met by the offered correction of (110) in accordance with the respondent's main request. As pointed out in G 11/91 at point 6 of the reasons, last sentence, the existence of a doubt precludes the permissibilty of corrective amendment. Here the board judges that the appellant opponent has convincingly shown that such a doubt exists, at least as regards the choice of the "correct" value.

5.3. As regards the offered correction of deletion without replacement the board judges this to be quite implausible. Although it is a usual pragmatic practice for a reader who encounters a term in a document which is unintelligible in context to proceed at first by ignoring the term and trying to make sense of the rest of the document, this kind of next and best resort of making do with what one has is ipso facto not a way of divining the author's intention in relation to the unintelligible term, so as to be able to correct the latter. The doubt as to the likelihood that the drafter of the application as filed while writing "in the (111) direction" intended not to refer to any direction whatever, which would be the effect of the proposed corrective amendment, is so great, in the judgement of the board, as to border on certainty. The fact that a term or phrase cannot be interpreted or construed because it is unresolvably ambiguous does not necessarily mean that its deletion is a permissible amendment under Article 123(2) EPC; there remains a residual clear meaning in the ambiguous term, eg, as in the present case, that a specific direction was taught and suppressing this fact results in a different technical teaching. In the unamended text the reader is taught that the direction is significant, in the proposed amended text the reader is taught, at least implicitly, that the direction is not significant.

5.3.1. Hence the board concludes that the second precondition of being immediately evident that nothing else would have been intended than what is offered as the correction, is not met by the offered correction of deletion of (111) without replacement (other than consequential grammatical amendment) in accordance with the respondent's first and second auxiliary requests.

6. Since all the respondent proprietor's requests involve amendments to the application or patent which are not permissible under Article 123(2) EPC, they all fall to be refused.