Whilst documents relevant only to other inventions may be retrieved during the search on the invention first mentioned in the claims, these are not necessarily included in the partial European search report. Such documents must, however, be cited in the partial search report if they form the basis for a lack of unity a posteriori (see F‑V, 5 and F-V, 7).
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/b_vii_1_3.htm
Date retrieved: 17 May 2021