10.2 Deciding what is to be considered the main invention 

The main invention will normally be the invention first mentioned in the claims. However, the examiner will exercise due discretion in selecting the invention to be searched where the first mentioned invention is one for which no search report would be established, or else where the applicant has requested that the supplementary search should be limited to one of the inventions other than the first identified by the ISA responsible for the main international search. For details, see GL/PCT‑EPO B‑XII, 10.3.