Mistakes in a document do not in themselves constitute prior art such as to prevent the grant of a patent.
In T 77/87 (OJ 1990, 280) the abstract published in the journal "Chemical Abstracts" did not correctly reproduce the original paper. The board stated that the original document was the primary source of what had been made available as a technical teaching. Where there was a substantial inconsistency between the original document and its abstract, it was clearly the disclosure of the original document that had to prevail. The disclosure in the original document provided the strongest evidence as to what had been made available to the skilled person. When it was clear from related, contemporaneously available evidence that the literal disclosure of a document was erroneous and did not represent the intended technical reality, such an erroneous disclosure should not be considered part of the state of the art.
In T 591/90 a prior document again contained mistakes. The board distinguished this case from T 77/87 (OJ 1990, 280), which had concerned a special case, and took the view that a document normally formed part of the prior art even if its disclosure was deficient. In evaluating such a disclosure it was to be assumed, however, that the skilled reader was mainly "interested in technical reality". Using his general technical knowledge and consulting the reference literature, he could see at once that the information in question was not correct. It could be assumed that a skilled person would try to correct recognisable errors, but not that he would take the deficient disclosure as pointing the way towards a solution to an existing technical problem.
In T 412/91 the board took the view, having regard to Art. 54 EPC 1973, that the incorrect teaching of document (1) was not comprised in the state of the art. It stated that, in principle, what constituted the disclosure of a prior art document was governed not merely by the words actually used in its disclosure, but also by what the publication revealed to the skilled person as a matter of technical reality. If a statement was plainly wrong, whether because of its inherent improbability or because other material showed that it was wrong, then - although published - it did not form part of the state of the art. Conversely, if the skilled person could not see the statement was wrong, then it did form part of the prior art.
In T 89/87 the board found that "0.005 mm" (= 5 nm) was a misprint contained in the prior document and that only "0.0005 mm" (= 0.5 nm) was correct. The board stated that the correction was such that the skilled reader would be expected to make it as a matter of course.
In T 230/01 the board noted that in Art. 54(2) EPC 1973 "the state of the art" was clearly and unambiguously defined as "everything made available to the public by means of a written or oral description, by use, or in any other way, before the date of filing of the European patent application". A document normally forms part of the state of the art, even if its disclosure is deficient, unless it can unequivocally be proven that the disclosure of the document is not enabling, or that the literal disclosure of the document is manifestly erroneous and does not represent the intended technical reality. Such a non-enabling or erroneous disclosure should then not be considered part of the state of the art (T 77/87, OJ 1990, 280; T 591/90).