When the invention is compared for novelty purposes with the state of the art as determined by applying the criteria described above, this must be done only on the basis of each element of prior art taken as a whole (see T 153/85, OJ 1988, 1; T 124/87, OJ 1989, 491; T 233/90, T 904/91).
If, however, there is a specific reference in one prior document (the "primary document") to a second prior document, when construing the primary document (i.e. determining what it means to the skilled person) the presence of such a specific reference may necessitate part or all of the disclosure of the second document being considered as part of the disclosure of the primary document (see T 153/85, OJ 1988, 1; T 645/91, T 942/91, T 422/92, T 866/93, T 866/93, T 239/94).
According to the boards' settled case law, a strict approach must be taken to assessing novelty and, in cases of ambiguity or doubt, the content of a prior publication must be interpreted narrowly (see T 447/92, T 988/95, T 722/00).
In T 291/85 (OJ 1988, 302) the board noted that the disclosure in a prior publication always included not only what it presented as the teaching of the invention but also what it referred to as the prior art. In the board's view, however, when examining for novelty, to read into an account of the state of the art couched in very general terms specific details of the inventive teaching of the same document was permissible only where a person skilled in the art would in fact have made this combination when reading this document. This would, for instance, be the case if a source were to be cited for the prior art described and a specific, relevant disclosure could be derived from the original document, or if the description of the prior art referred directly to the appropriate passage in the description of the invention. Combining a specific feature from the description with the general description of the prior art in this way might, in certain circumstances, be obvious to a skilled person merely in the light of his general technical knowledge. In the absence of such or similar circumstances, however, one could not, in the board's view, assume that a skilled person would necessarily have derived from the document a teaching based on a combination of this kind. Thus, the board concluded that if a citation gave detailed information about a further development of a prior art described only in very general terms without quoting a specific source, it was not permissible in examining for novelty to combine these general statements with the specific statements made solely in order to explain the said development, unless a person skilled in the art would have made the combination when reading the citation.
In T 288/90 the board observed that, although for the purposes of assessing novelty it was not normally legitimate to read two documents together, nevertheless, when interpreting a single document, it was necessary to read it having the general technical knowledge in mind, and for this purpose to look at representative technical literature as an aid to the correct interpretation of any particular term of art encountered.
In decision T 56/87 (OJ 1990, 188) the board emphasised that the technical disclosure in a document should be considered in its entirety, as it would be by a person skilled in the art, and that there could be no justification for arbitrarily isolating parts of the document in order to derive therefrom an item of technical information which would be distinct from or even contradict the integral teaching of the document. Therefore, the board considered that a particular feature relating to the positioning of the outer electrodes of a transmission ion chamber, in such a way that they partially lay in the shadow of a collimator, for implementing a process for correcting alignment errors of a divergent beam of rays, was not disclosed in a prior art document which, however, contained a figure in which such positioning could be identified. The reason was that the figure in question was obviously a schematic illustration showing neither the proportions nor the dimensions of the actual apparatus. In order to be able to interpret it correctly, the skilled technician therefore had to refer to the other figures and to the written description of the document; he would have deduced from the latter, however, that the outer electrodes should be positioned entirely in the radiation field, and not partially in the shadow of the collimators, as set out in the claims examined (see T 332/87, T 441/91 and T 657/92).