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 239/94; T 221/05).

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, T 1517/11).

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. 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. Thus, a technical feature which was derived from or based on dimensions obtained from a schematic illustration and which technically contradicted the teaching of the description did not form part of the disclosure of this document (see T 332/87, T 441/91 and T 657/92).