4.2 Use of "P" documents in the written opinion 

If the priority document is not available, the opinion will be established on the assumption that the claimed priority is valid. In this case, no comments need be made regarding "P" documents, but the "P" documents will nevertheless be indicated under Section VI. For potentially conflicting patent documents which might give rise to an objection under Art. 54(3) EPC in the European phase, the statements in GL/PCT‑EPO B‑XI, 4.3, below regarding "E" documents apply.

If the priority document is available, the examiner will check the validity of the priority and indicate any negative finding under Section II. Should the priority be found not to be valid, detailed comments will be made for these documents with respect to novelty and inventive step of the claimed subject-matter under Section V, since these documents then become prior art under Rule 33.1(a).

Sometimes it is possible for the examiner to determine from the documents on file that the claimed priority is not valid. An example would be when during the search a document is found which shows that the priority document of the searched application is actually not the first application for the claimed invention.