Type Alias Variant

Variant: "hierarchical" | "absolute" | "internal" | "relative"

Identifier variant per RFC 3986 §§ 4.2-4.3.

"hierarchical": Absolute with hierarchical path (http://example.org/path, app:/path)
"absolute": Contains scheme (http://example.org/path, urn:example:resource)
"internal": Root-relative path starting with / (/path)
"relative": Reference without scheme (../path, path)

Variants form an inclusivity hierarchy: hierarchical ⊂ absolute ⊂ internal ⊂ relative
The "hierarchical" variant requires an absolute URI with a path starting with /; authority is optional per RFC 3986 § 3 hier-part grammar (path-absolute alternative); reference resolution is supported per RFC 3986 § 5.2.3
The "internal" variant is project-specific, not formally defined in RFC 3986
For non-hierarchical (opaque) URIs such as urn: or mailto:, reference operations adapt:
- resolve: Throws RangeError for relative references (no standard resolution)
- internalize: Returns scheme-specific part if schemes match
- relativize: Returns scheme-specific part if schemes match