2.4.4 A situation in which it has to be checked whether the application from which priority is actually claimed is the "first application" within the meaning of Art. 87(1)

P1 is the earliest application of the same applicant containing the invention. EP claims the priority of the later US application P2, which is a "continuation-in-part" of P1. D is a public disclosure of A+B.

The priority claim of P2 for claim 1 is not valid as P2 is not the "first application" for this subject-matter within the meaning of Art. 87(1), but P1 is, which has "left rights outstanding" in that P2 is a "continuation-in-part" thereof. Therefore Art. 87(4) does not apply and this is not altered by an abandonment, withdrawal, refusal or non-publication of P1. D is prior art pursuant to Art. 54(2) against claim 1, but not against claim 2, as the latter claim has the earlier priority of P2.