Exceptionally, where the application covers two or more technical fields which are so diverse that a member trained to carry out searches in one of those fields cannot reasonably be expected to carry out a search in all of them, the responsibility for preparing the search report may be shared between a number of members.
The skills required to carry out a search in a particular technical field consist of two aspects, viz.:
If the subject-matter of the application extends over different technical fields it might be appropriate to expand the search division to include a second and possibly further member(s) specialised in those fields.
In all the above cases, the search report and search opinion (if applicable, see B‑XI, 7) are usually issued by one member only.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/b_i_2_2_1.htm
Date retrieved: 17 May 2021