If applicants have not availed themselves of the opportunity to have the search results on the other inventions included in the search report because they have paid no additional search fees in response to the invitation under Rule 64(1) (see B‑VII, 1.2) or Rule 164(1) (see B‑VII, 2.3), they will be taken to have elected that the application should proceed on the basis of the invention which has been searched (see G 2/92). In cases where a communication according to Rule 164(2) has been sent, Rule 164(2)(c) requires the applicant to delete all unsearched inventions from the claims.
It must be taken into account that the final responsibility for establishing whether the application meets the requirement of unity of invention ultimately rests with the examining division (see T 631/97). When considering the issue of unity, the examining division will consider both the reasons given in the search opinion and the applicant's response thereto (see B‑XI, 8, for details of when a response to the search opinion is required); for Euro-PCT cases where no supplementary European search report is prepared, the examining division will consider the reasons given in the WO‑ISA, IPER or supplementary international search report prepared by the EPO and the applicant's response thereto as required by Rule 161(1) (see E‑IX, 3.2). In the absence of any convincing response from the applicant to the issue of unity as raised earlier, the examining division will normally initially uphold the position taken earlier (see B‑XI, 1.2) and will then require deletion of all the inventions other than that which has been searched. If the examining division is convinced, e.g. by arguments from the applicant, that the opinion on unity at the search stage was incorrect, then an additional search is performed for that part of the subject-matter which is judged to be unitary with an invention which was searched (see B‑II, 4.2(iii), and C‑IV, 7.2) and the examination is carried out on those claims which comply with the requirement of unity of invention. The applicant may file a divisional application for any excised subject-matter (see C‑III, 3.2).