For international applications entering the European phase with an international search report established by an ISA other than the EPO, a supplementary European search is carried out by the Search Division in the cases listed in B-II, 4.3.2. If the Search Division, during the supplementary European search, notes a lack of unity, B-VII, 2.3 applies. The search opinion accompanying the supplementary European search report deals only with the invention (or unitary group of inventions) first mentioned in the claims serving as basis for the supplementary search report (Rule 164(1)).
The procedure before the Examining Division in such cases is described in E-VIII, 4.2. In brief, the examiner will normally proceed solely with the examination of said first invention (or group of inventions). There is no choice under Rule 164(2) because the only invention searched by the EPO is the one searched in the supplementary European search report by virtue of Rule 164(1) (see also F-V, 11).