Overview: External identifiers
External identifiers name entries within a particular provider or catalogue namespace.
An identifier is meaningful within the system that assigned it. IMDb and MusicBrainz IDs connect to different kinds of catalogue records, and a provider ID should retain that context when it travels through a file or library. The pages here explain the record being identified rather than treating every ID as a universal title key.
Provider identifiers
A provider identifier names a record within a provider's namespace and entity model, independently of a local file path or displayed title.IMDb identifiers
IMDb identifiers distinguish catalogue title and person records, with published dataset fields preserving the keys as strings and recording entity relationships separately.MusicBrainz identifiers
MusicBrainz identifiers are UUID-shaped keys for distinct music entities, so recording, release and release-group references must retain their intended scope.