The "internal" variant is a project-specific subset of relative references, not formally defined in RFC 3986.
For opaque URIs (e.g., urn:, mailto:), reference operations adapt their behavior:
RangeError for relative references (no standard resolution)example:resource from urn:)
Identifier variant per RFC 3986 §§ 4.2-4.3.
"absolute": Contains scheme (e.g.,http://example.org/path,urn:example:resource)"internal": Root-relative path starting with/(e.g.,/path)"relative": Reference without scheme (e.g.,../path,path)