The USPTO participates in the electronic priority document exchange (PDX) program. Use of PDX avoids the fee associated with ordering a certified priority document for each office of subsequent filing and the costs of transmitting those certified copies to foreign associates or foreign intellectual property (IP) offices. The USPTO transmits certain U.S. priority applications as-filed to any foreign IP office that participates in the priority document exchange program (participating office) and retrieves/accesses certain foreign priority applications as-filed from the participating offices. The priority document exchange program includes two modes of exchange: Direct Bilateral Exchange and World Intellectual Property Organization Digital Access Service (WIPO DAS) Exchange.