2.12 Lack of unity 

When the claims of the international application do not relate to one invention only, or to a group of inventions so linked as to form a single general inventive concept, the applicant will normally be invited to pay additional search fees. If the applicant does not pay any additional search fees in response to the invitation, the international search will normally be restricted to those parts that relate to the invention, or so linked group of inventions, first mentioned in the claims. If additional fees have been paid within the prescribed time limit, those parts that relate to the inventions covered thereby are also searched. See also GL/PCT‑EPO B‑VII.