Each general chapter is assigned a number that appears in brackets adjacent to the chapter name (e.g., 621 Chromatography). Articles recognized in these compendia must comply with the official standards and tests and assays in the General Notices, relevant monographs, and General Chapters numbered below 1000. General Chapters numbered above 1000 are considered interpretive and are intended to provide information on, give definition to, or describe a particular subject. They contain no official standards, tests, assays, or other mandatory requirements applicable to any Pharmacopeial article unless specifically referenced in a monograph or elsewhere in the Pharmacopeia.

The use of the general chapter numbers is encouraged for identification of and rapid access to general tests and information. It is especially helpful where monograph section headings and chapter names are not the same (e.g., Ultraviolet Absorption 197U in a monograph refers to method 197U under general tests chapter 197 Spectrophotometric Identification Tests; Specific rotation 781S in a monograph refers to method 781S under general tests chapter 781 Optical Rotation; and Calcium 191 in a monograph refers to the tests for Calcium under general tests chapter 191 Identification Tests—General).