The analysis used to determine whether the Office may require restriction differs in national stage applications submitted under 35 U.S.C. 371 (unity of invention analysis) as compared to national applications filed under 35 U.S.C. 111(a) (independent and distinct analysis). See MPEP Chapter 1800, in particular MPEP § 1850, § 1875, and § 1893.03(d), for a detailed discussion of unity of invention under the Patent Cooperation Treaty (PCT). However, the guidance set forth in this chapter with regard to other substantive and procedural matters (e.g., double patenting rejections (MPEP § 804), election and reply by applicant (MPEP § 818), and rejoinder of nonelected inventions (MPEP § 821.04) generally applies to national stage applications submitted under 35 U.S.C. 371.