Subidentifier

Subidentifier is a term used to describe a component that forms part of a larger identifier in computer systems, data models, and information architectures. It designates a subcomponent, subresource, or subnamespace within a hierarchical naming scheme, helping to address nested elements with precision. The term is descriptive rather than normative, and its exact interpretation can vary by domain.

In practice, subidentifiers are separated from the main identifier by a delimiter such as a dot, colon, slash, or hyphen. Examples include domain.subdomain.resource.subresource, urn:example:resource:subresource, and a REST API path like /api/v1/users/12345, where v1 and users introduce sublevels within the overall resource locator.

Common use cases include namespace and resource scoping, versioning, file systems, and data models. In file systems, a path like /home/user/documents/report.pdf uses subidentifiers to locate a nested file. In URIs and URLs, subidentifiers facilitate navigation to nested resources. In data schemas, a type such as Person.name or Address.street uses subidentifiers to qualify attributes or subtypes.

Handling and processing subidentifiers typically involves parsing the string into a sequence of lexemes, validation against a grammar, and semantic resolution to a target object or resource. Systems may support normalization rules, such as case folding, delimiter standardization, or trimming of whitespace, to enable reliable comparisons and lookups.

Because there is no universal standard for subidentifiers, implementations emphasize consistency within a given domain, clear documentation of the delimiter and ordering rules, and backward compatibility when extending an identifier. The concept is closely related to hierarchical naming, resource addressing, and composite keys in databases.