A US patent application can be either a national application filed directly as such at the US Patent office or an application which has entered the national phase from an international application filed under the Patent Cooperation Treaty.

The treatment at the Patent office is the same except for two exceptions:

(1)  Restriction practice  (see ch. 800) applies to national applications while unity of invention applies to unity national stage applications; and

(2)  National applications filed without an oath or declaration are awarded a filing date and the applicant is sent a “Notice of Missing Parts.”  National Stage applications do not get a filing date until the inventor’s Oath or Declaration is filed and the filing fee is paid.