4.3 Use of "E" documents in the written opinion 

Although there are no harmonised provisions in the PCT Contracting States that correspond to Art. 54(3) EPC, such documents will be mentioned under Section VI if they are considered prejudicial to the novelty of at least one claim. If the relevance of the document is independent of the priority being valid or if the priority could be checked and was found invalid, reasons for the novelty objection will be provided, together with an indication that such a document would be relevant when entering the European phase before the EPO.

On the other hand, if the document would be relevant under Art. 54(3) EPC only if the priority is not valid, and this could not be checked, then no reasons need to be given.