In T 6/84 (OJ 1985, 238) the board took the view that structural features of a means for performing a chemical process (here the catalyst "offretite"), which were not mentioned in the application documents themselves but in a document (here a Canadian patent specification) to which they referred, could be incorporated into a patent claim if they unequivocally formed part of the invention for which protection was sought (see also T 590/94). However, it was not permissible to single out a particular one of their number (here a silica/alumina ratio) in the absence of evidence that this feature alone was a sufficient characterisation. It was instead necessary to recite fully the other essential components of the structure and the diffraction pattern figures which belonged together, as originally disclosed and defined in that document.
In T 689/90 (OJ 1993, 616) the board decided that features disclosed only in a cross-referenced document which was identified in the description as filed were prima facie not within "the content of the application as filed". Only under particular conditions would adding them to a claim not be an infringement of Art. 123(2) EPC 1973, namely if (a) the description of the invention as filed left the skilled reader in no doubt that protection was sought for those features; (b) they helped achieve the invention's technical aim and thus formed part of the solution to the technical problem underlying the invention claimed; (c) they implicitly clearly belonged to the description of the invention contained in the application as filed (Art. 78(1)(b) EPC 1973) and thus to the content of the application as filed (Art. 123(2) EPC 1973); and (d) they were precisely defined and identifiable within the total technical information contained in the reference document. In the case at issue these requirements were not fulfilled. See also T 196/92, T 558/03, T 1497/06, T 1415/07, T 1378/08, T 664/11, T 1451/12, T 2498/12, T 672/14; see also T 474/05 in which the reference in the application to a document was within a specific context, and the amendment went beyond this context and was thus not allowable; see also T 2477/12, applying T 689/90 in the context of Art. 76(1) EPC where the priority application, containing sequence listings, had been "incorporated by reference" in the parent application.
In T 737/90 the board held that a cross-referenced document could only be taken into account if the relevant addressees of the application containing the reference had ready access to the referenced document (the EPO before publication of the application and the public after it).