A USPTO Provisional Application (PPA) has been submitted and a NPA is to be drafted. That being said,
What needs to be done \ avoided to maintain eligibility to file a European Application?
What is the "Gap" between a NPA and a European Application?
In and ideal world, the NPA filed in the US would be enough to file in EU.
While there are international treaties regarding patent systems, the laws and procedures of the USPTO and the EPO are not the same. However, many EPO filings from US applicants are just a reformating of their U.S. applications. In general, the EPO is more strict, particularly on claiming combinations and permutations of feature and the charge for excess claims is more severe in the EPO. That is offset by the use of a type of claiming allowed but heavily discouraged in the the U.S.
If an applicant thinks of a U.S. provisional application as something that can be less detailed than a "real" application, the chance that it would be a good EPO application is significantly reduced.
If priority is to be claimed it needs to be claimed within one year of the first filing.
Excerpt from art. 87 EPC:
a right of priority during a period of twelve months from the date of filing of the first application.
The first filing is the provisional. It is not the non provisional.
There is no way around that, if you file a non provisional 1 year after the provisional, you cannot claim priority to any of those later in Europe.
