T 196/92 offers a summary of the teaching of T 6/84 and T 689/90. In T 6/84, (OJ 1985, 238), wherein it was decided that structural features not mentioned in the application documents themselves but in a document to which they refer may be incorporated into the patent claim if they unequivocally form part of the invention for which protection is sought and if all the essential structural features which belong together, as disclosed in such document, are incorporated into the claim. Moreover, this position was confirmed in decision T 689/90 (OJ 1993, 616), wherein it was further specified that features mentioned only in a cross-referenced document may be incorporated into the wording of a claim if the invention as filed leaves no doubt that such features contribute to achieving the technical aim of the invention and if such features are precisely defined and identifiable within the total technical information within the reference document.
In T 6/84 (OJ 1985, 238) the subject-matter of the application was a chemical process solely characterised in that the catalyst was synthetic offretite having a silica/alumina mole ratio of 5 to 10. For the definition of synthetic offretite the description referred to a Canadian patent specification. 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 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 6/84 it was clear having regard to the facts that the further characterising parameters of synthetic offretite which were included in the main claim by way of amendment were indeed features which unequivocally formed part of the invention for which protection was already sought, because the use of synthetic offretite as a catalyst was already the only characterising feature in the claim as originally filed, and the features which were added to that claim simply defined such synthetic offretite better.
In T 689/90 (OJ 1993, 616), however, the description of the invention as originally filed did not in any way suggest that the "further details" of a certain feature to be found in a document D1 referred to and now to be included in the main claim were intended to identify features of the invention for which protection might be sought or that such features implicitly clearly belonged to the description of the invention. 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 the description of the invention as filed left the skilled reader in no doubt that protection was sought for those features; that they helped achieve the invention's technical aim and thus formed part of the solution to the technical problem underlying the invention claimed; that they implicitly clearly belonged to the description of the invention contained in the application as filed and thus to the content of the application as filed, and that 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 1497/06, in which the board examined T 689/90; and T 1415/07, in which the board reiterated the four conditions imposed in T 689/90).