OptionalcontentPreserved MIME type when provided.
OptionaletagOpaque backend generation/entity identifier; not necessarily a content hash.
Logical relative ASCII key, independent of a configured physical prefix/root.
OptionallastISO 8601 timestamp when available.
OptionalmetadataPreserved portable user metadata.
Stored body length in bytes.
OptionalversionBackend object version identifier when supported and returned.
Portable metadata for one logical object; backend-specific identifiers are optional and opaque.