Under Art. 82 EPC, as under R. 13.1 PCT, the application must relate to one invention only or to a group of inventions so linked as to form a single general inventive concept. The second alternative, i.e. the single-concept linked group, may give rise to a plurality of independent claims in the same or different categories (see also R. 43(2) EPC).

The question has arisen on a number of occasions as to whether part of, or an annex to, the description of a European patent application comprising a series of numbered paragraphs drawn up in the form of claims should be regarded as claims for the purposes of R. 31(1) EPC 1973.