Cases will arise where the application does not comply with Rule 43(2) (see B‑VIII, 4.1 and F‑IV, 3.2) and the application also lacks unity of invention according to Art. 82 and Rule 44. It may be appropriate to raise only the issue of unity of invention and send an invitation under Rule 64(1) (see B‑VII, 1.1 and B-VII, 1.2).
It may, however, be necessary to apply the procedures under both Rule 64(1) (invitation to pay additional search fees for inventions other that the first mentioned in the claims) and Rule 62a(1). In this case, the EPO will first send the applicant an invitation according to Rule 62a(1), requesting him to indicate the independent claims to be searched.
In cases where the lack of unity is already apparent when the invitation under Rule 62a(1) is sent, it will also identify the first invention mentioned in the claims and the claims which relate to this invention, either in full or in part, and will invite the applicant to indicate which claims to search in respect of this invention first mentioned in the claims. After expiry of the time limit according to Rule 62a(1), the claims to be searched in respect of the first invention will be determined according to the procedures specified in B‑VIII, 4.2. A partial search report will then be prepared on the invention first mentioned in the claims. This will be sent to the applicant along with a provisional opinion on the patentability of the invention or unitary group of inventions first mentioned in the claims, the reasons for the non-unity findings and an invitation to pay additional search fees under Rule 64(1) in respect of the other inventions. Where appropriate, this invitation under Rule 64(1) may also include an invitation according to Rule 62a(1), requesting the applicant to clarify the claims to be searched in respect of any additional inventions for which he subsequently pays additional search fees.
Conversely, it may also happen that after an invitation is sent according to Rule 62a(1) in respect of all claims, the claims which satisfy Rule 43(2) and which are subject to a search (as determined according to the procedures given in B‑VIII, 4.2) are subject to an objection of lack of unity a posteriori. In such cases, an invitation to pay additional fees under Rule 64(1) will then be sent, the invitation being based only on the subject-matter of the claims determined by the applicant's response (or failure to respond) to the invitation under Rule 62a(1).