This decision also contains some interesting paragraphs on how oppositions have to be substantiated, in particular when non-patent documents are cited.
*** Translation of the German original ***
 According to the established case law of the Boards of appeal, the requirement that [the opponent has] to provide an indication of the relevant facts and evidence (R 55(c) EPC 1973, last half sentence) is only met if the relevant facts and evidence are indicated so that they allow the Opposition Division (OD) and the patent proprietor to correctly understand the grounds for opposition that are invoked and their validity (Stichhaltigkeit) without further investigations, so that they can comment on them (cf. T 2/89 and T 328/87). The requirement “indication of the facts and evidence presented in support of the grounds” has to be understood to mean all facts on which the opponent bases the request to revoke the patent. In other words, the justification (Begründung) of the opposition has to present the circumstances that are relevant for the assessment of the ground for opposition that is invoked. Which circumstances are relevant depends on the individual case and follows from the overall context (cf. T 222/85). It is not possible to remedy deficiencies after the expiration of the time limit for filing an opposition if the justification of the opposition is insufficient (see T 522/94). In order to meet the requirements of R 55(c) EPC 1973, last half sentence, it is sufficient if one ground for opposition is sufficiently substantiated. One single substantiated objection, such as for example the objection of lack of novelty based on one of the documents, is sufficient to reach this goal.
 In the present case the opponent has cited the grounds for opposition “lack of novelty” and “lack of inventive step” as well as the ground for opposition pursuant to A 100(c) EPC 1973 in the opposition form, but in the justification only the ground for opposition “lack of inventive step” was explained in more detail: document A1 (JP 58224226 A (Abstract)) was discussed in combination with documents A3 and A5. Point 3.2 of the notice of opposition also cites document A8 (DE 196 01 517 A1), but only in combination with the above mentioned documents, i.e. in connection with A1 and A3 and A1 and A5, respectively. Thus the indication of the facts and evidence presented in support of this ground within the meaning of R 55(c) EPC 1973 is limited to the objection of lack of inventive step. The opposition form does not contain any explanations regarding the grounds for opposition “lack of novelty” and A 100(c) EPC 1973. However, this does not have any influence on the admissibility of the opposition, because the notion of inadmissibility pursuant to R 56 EPC 1973 only refers to the opposition as a whole. If the requirements regarding admissibility are met for at least one ground for opposition, the opposition is admissible as a whole (see T 212/97).
 The explanations of the [opponent] regarding substantiation essentially consists in the following chain of arguments:
(a) R 55 EPC 1973 does not provide that documents cited against [the opposed patent] have to be dated or that their date (Zeitrang) has to be indicated;
(b) even if there was a requirement regarding [their] date, the dates provided on the opposition form met this requirement;
(c) the above mentioned dates are to be understood as print dates – regarding these dates one had to assume a prior publication (Vorveröffentlichung) of documents A3 and A5;
(d) the question of whether there had indeed been a prior publication was only to be examined when the allowability of the opposition was examined.
 As far as the first objection is concerned, it has to be noted that the facts and evidence presented in support of the ground for opposition within the meaning of R 55(c) EPC 1973 have to be provided for each ground for opposition. The ground for opposition “inventive step” in any case requires the indication of the relevant prior art on which the assessment of the inventive step is to be based in the opposition proceedings. In the present case the ground for opposition “inventive step” is based on a combination of documents A1 and A3, A1 and A5 as well as document A8 which is cited in the context of combinations of A1 and A3 and A1 and A5, respectively.
As a rule there is no need for explanations regarding the fact that patent documents have been published at a certain date, i.e. have to be considered as prior art, because the documents themselves provide a reliable (gesichert) publication date. In the present case, this applies to documents A1 and A8 because they are classical patent documents. However, if documents that do not disclose a reliable publication date are cited, it is necessary to discuss in detail the question of whether they belong to the prior art, i.e. the question of the date and circumstances of their publication, which is fundamental for the ground for opposition “inventive step”. In the present case, the documents A3 and A5 are not patent documents which themselves provide a reliable publication date, but assembly instructions (A3) and a company brochure (A5). As a rule, such documents do not contain a date of publication but at best an encoded print date or a date related to the prior art taken into account in the document, or the editorial deadline (Redaktionsschluss). In such documents, which are not classical patent publications, the requirement of substantiation is, as a rule, only met if [the opponent] cites concrete facts from which one can derive that they have been made available to the public before the priority date (cf. Podbielski, in: Singer/Stauder, EPÜ, 6th edition, A 99, marginal number 87, which cites further authorities). Thus the presentation of the facts has to be such that it can be understood without further ado when and under which circumstances the alleged prior publication has occurred.
Therefore, the first objection of the [opponent] cannot succeed.
 Regarding the second objection of the [opponent], the following should be noted: In the case under consideration the documents A3 and A5 have been designated as “Company brochure assembly instructions CERAPUR (Ju 1336/1) February 1996” (A3) and “Company brochure Vaillant Thermoblock Klassik Heating Value VC/VCW 196 E-C, August 1998” (A5).
There were no further explanations regarding the above mentioned dates and the circumstances of a possible prior publication within the time limit for filing an opposition. Thus the question arises whether the [opponent] has met its duty of substantiation as to when and how the cited documents A3 and A5 have been made available to the public. In this context it has to be noted that the [opponent] has dated these documents in the opposition form, i.e. “February 1996” for A3 and “August 1998” for A5 – but that it has not pointed out whether these dates were to be understood as print or publication dates. Moreover, it is to be noted that there are no explanations in the notice of opposition as to whether these dates were taken from the documents themselves or from which pieces of information, possibly contained in the documents, they were derived. The Board is of the opinion that the dates are not disclosed in the documents themselves. As explained in the decision of the OD, document A3 contains several combinations of letters and numbers that can be interpreted as indications of date. First, on the right upper corner of the cover sheet there is the indication:
Moreover, on the right upper corner of the cover sheet there is the indication:
And on the last page (page 34) in the middle of the right margin there is the indication “11/95”:
The notice of opposition only contains the date “February 1996” without any further discussion of or reference to the information contained in A3. It is only in its letter dated September 30, 2005, i.e. after expiration of the time limit for filing an opposition, that the opponent has explained that the indication “JU 1336/1, 6 720 603 928 (2.96) PC - Pf” referred to the print date. For the sake of completeness, it also has to be mentioned that in the course of the oral proceedings on May 17, 2013, the [opponent] has explained, in view of the indication on the cover sheet (“29.09.95”) that this was the date of clearance (Freigabe). The fact that a document that was allegedly printed in the year 1996 contains a clearance date of 1995 remains unexplained. In any case, it cannot be the clearance of the present document A3, which was said to have been printed in 1996.
 As far as A5 is concerned, it has to be noted that this document also contains several combinations of figures and letters that can be interpreted as indications of date. First, the upper right corner of the cover sheet and the bottom of the right margin of the last page both contain the indication
And the bottom of the right margin of the last page contains the indication “subject to change A/0898 87 6108”:
In its letter dated September 30, 2005, i.e. after expiration after the time limit for filing an opposition, the opponent has explained that the latter indication allowed to derive a print date of “August 1998”.
 In view of what has been said above, the Board of appeal (BoA) reaches the conclusion that because of the ambiguity of the letter-number combinations in documents A3 and A5 the dates provided in the opposition form cannot be unambiguously derived from the documents themselves. Moreover, even when taking account of the contents of documents A3 and A5 it was not apparent whether the opponent wanted these dates to be understood as print or publication dates. For this reason alone it would have been necessary to discuss in more detail the question of the dates of the above mentioned documents within the time limit for filing an opposition. Moreover, it should be noted that – even if the later submissions of the [opponent] are considered – the dates contained in the opposition form are only print dates. Thus, even the submissions of the [opponent] lead to the conclusion that the question of the date, which is relevant for the requirement of substantiation, and of the circumstances of the alleged prior publications has not been discussed (thematisiert) at all within the time limit for filing an opposition. Thus the BoA is of the opinion that for the above mentioned reasons alone there is a lack of substantiation resulting in the inadmissibility of the opposition.
 For the sake of completeness, however, the [Board] wishes to make the following comment on the third objection of the [opponent] (see point  above). The [opponent] is of the opinion that the dates mentioned in the notice of opposition are to be understood as print dates, and consequently one has to assume a prior publication of documents A3 and A5, and the opposition is sufficiently substantiated. First it has to be noted that, as mentioned above, the BoA does not endorse this approach, be it only because the dates provided in the opposition form were not unambiguously to be understood as print dates. But even if one assumes that the indication “JU 1336/1, 6 720 603 928 (2.96) PC - Pf” refers to the date on which A3 was printed – as alleged by the [opponent] – this does not say anything about the date of publication, which is decisive for the determination of the prior art. The BoA is of the opinion that in this context it also has to be taken into account that document A3 provides assembly instructions. Usually assembly and installation instructions are not properly “published” but are made available to the public together with the product that is to be assembled or installed (cf. T 511/02). The corresponding information cannot be deduced from A3 itself, nor does the notice of opposition provide any indication on possible sales of the product or a distribution of the assembly instructions related to such sales.
 As regards A5, it has to be noted that it apparently is a company brochure of the [opponent]. It is true indeed that, as a rule, a brochure that is directed at clients may be assumed to be distributed to potential customers shortly after the print date, so that the indication of the print date may be sufficient under certain circumstances (see T 597/07 and T 782/04). However, in the present case the BoA is of the opinion that it is necessary to take account of the fact that the opposition form only contains the indication “August 1998” without any further explanation whether the opponent understands this date to be a date of print, of publication or an editorial deadline. Moreover, there is no indication as to whether this date was derived from information contained in the document itself. This, however, appears to be required in the present case because, as mentioned above, A5 contains several letter-number combinations which might serve as a basis for dating the document. However, even if the indication “subject to change A/0898 87 6108” on the last page of A5 is used and interpreted as a date, this date cannot be readily understood to be a print date. Rather, the indication “subject to change” suggests that this was intended to establish the editorial deadline or the prior art taken into account in the brochure. The Board is of the opinion that in the present case it also has to be taken into account that the patent under consideration claims a priority date of March 14, 1999, i.e. a date which is only about 8 to 9 months after the above mentioned date (“August 1998”). If one assumes that “August 1998” designates the prior art taken into account in the brochure or the editorial deadline, then one may not simply assume that [the document] has been published before the priority date because usually there is quite some time between the editorial deadline and the printing (Drucklegung) and a subsequent publication, which itself may be quite some time before the distribution of the brochures, irrespective of the configurations mentioned by the OD, where the distribution of printed brochures does not take place at all, for technical or economic reasons (deficiency of the product, lack of compliance with technical standards, infringements, etc.). In this context the [patent proprietor] has pointed out that it is not unusual that printed brochures are not published in cases where the technology develops quickly or where there is a deficiency of the product which leads to the production of distribution of the products being stopped.
 The date and the circumstances of the publication are decisive for the assessment of whether the documents A3 and A5 belong to the prior art and, therefore, whether they can be cited against the patent at all. Thus a presentation of the corresponding facts would have been necessary for the justification of the ground for opposition “inventive step” in the present case. For the above mentioned reasons the BoA is of the opinion that the indications of dates contained in the opposition form, which have not been explained at all, do not comply with the requirement of substantiation expressed in R 55(c) EPC 1973, all the more so as the documents do not provide any indications helping to understand the dates given in the opposition form.
 In the statement of grounds of appeal the [opponent] also pointed out that it was not relevant for the admissibility whether the indications regarding the publication of the documents were proven; [the opponent expressed the opinion] that this was related to the allowability of the opposition but not to be dealt with when its admissibility was examined.
 In this context it has to be emphasized that it is necessary to distinguish between the requirement of substantiation and the question of whether an assertion regarding facts (Tatsachenvortrag) is considered to have been proven. When substantiation is to be examined, all that has to be examined is whether the relevant facts and evidence are indicated so that they allow the Opposition Division (OD) and the patent proprietor to correctly understand the grounds for opposition that are invoked and their validity (Stichhaltigkeit) without further investigations and whether they are enabled to comment on them (cf. T 2/89 and T 328/87 . The BoA has carried out the examination accordingly; it had to examine whether the factual assertion regarding the date and the circumstances of the publication of A3 and A5 was sufficient. There was a need for such an assertion because the documents cited are not patent documents which themselves provide a reliable publication date. The mere indication of dates without any further explanation of whether these date are publication dates at all and without any explanation regarding the basis for the dating cannot constitute a sufficient assertion of facts, all the more as the documents do not unambiguously disclose these dates. Moreover, it has to be taken into account that dates that may be contained in such documents usually refer to an editorial deadline or a print date but not the date of publication. Therefore, in view of the nature of the documents, the dates provided on the opposition form needed further explanation, which means that the factual assertions did not comply with the requirement of substantiation in this respect. Thus, what matters is not whether the dates provided were to be considered to have been proven, but only whether the submissions were sufficiently substantiated regarding the date and the circumstances of the publication of documents A3 and A5.
 As the requirement of substantiation has to be met within the time limit for filing an opposition and any deficiency of justification cannot be remedied after expiration of this time limit (see above, point ), neither the submissions of the [opponent] dated September 30, 2005, which contain further explanations regarding the publication of documents A3 and A5, nor the declaration in lieu of oath of Dr. Hocker, which has been filed during the oral proceedings before the OD, on November 15, 2010, can be taken into account when the substantiation [of the grounds for opposition] is examined. Also, the argument presented in the statement of grounds of appeal, according to which the documents A3 and A5 had only been filed in order to provide evidence for the general knowledge of the skilled person and accordingly, the attacks contained in the opposition are based on A1 in combination with the general knowledge of the skilled person, is not persuasive. When discussing the ground of inventive step, the notice of opposition expressly indicates that the skilled person, based on document A1, would consider the teaching contained in documents A3 and A5 in order to reach the subject-matter of claim 1 of the patent-in-suit […]. Thus the BoA cannot endorse the argument of the [opponent] according to which the documents A3 and A5 have only been introduced as evidence for the common technical knowledge.
 As already explained by the OD in […] its decision, the objections against inventive step which have been raised in the notice of opposition expressly rely on a combination of A1 and A3 or A5, respectively. Even if it was possible to object [to inventive step] based on document A1 in combination with the general knowledge of the skilled person, as first argued by the [opponent] during the oral proceedings before the OD […] and repeated in the statement of grounds of appeal, this does not mean that such an objection, which has only been raised after expiration of the time limit for filing an opposition can remedy the original lack of substantiation of the opposition. As mentioned above, the requirement of substantiation has to be met within the time limit for filing an opposition. Subsequent attempts of remedying deficiencies are not to be taken into account when this question is examined.
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