PCT Administrative Instructions Section 605.
File to be used for International Preliminary Examination
Where the International Preliminary Examining Authority is part of the same national Office or intergovernmental organization as the International Searching Authority, the same file shall serve the purposes of international search and international preliminary examination.
After the PCT International Application Processing Division has finished processing the documents and fees filed with a complete demand, the international application is docketed to an examiner in the appropriate Technology Center for examination. If the USPTO was the International Searching Authority for the international application, the same file used for purposes of the international search will be used for purposes of international preliminary examination.