U21B3

U21B3 is an alphanumeric designation used across diverse catalogs and systems. It does not refer to a single, universally recognized entity; rather, its meaning is determined by context and source. In manufacturing and electronics, U21B3 regularly appears as a model number or part code within a product family, where letters and numbers indicate series, revision level, or compatibility. In transportation databases, U21B3 can designate a specific service, route segment, or stop group within an agency’s internal numbering scheme. In software and data management, U21B3 may function as a build identifier, module code, or dataset label used to track versions or configurations.

Because the same string can occur independently in different domains, disambiguation is essential. Analysts and researchers should use contextual cues such as the issuing organization, accompanying identifiers (prefixes, suffixes, or date codes), and the source catalog to infer the intended reference. If possible, consult official documentation, product datasheets, transit authority timetables, or repository metadata. Without context, U21B3 has no universally agreed meaning.

See also: disambiguation, list of alphanumeric designations.