RealJukebox:Metadata - Contains binary metadata inserted by RealJukebox.
ASIN - Contains the ASIN for the song's album.
Catalog Number - Contains the catalog number for the song's album.
CDDB Discid - Contains the CDDB discid for the song's album (if lacking an MCDI tag).
CRC32 - Contains the CRC32 for the given file.
EAN/UPC - Contains the EAN or UPC for the song's album.
ED2K - Contains the ED2K hash for the given file.
GRid - Contains the GRid for the song's album.
ISAN - Contains the ISAN for the song's album (if applicable).
ISBN - Contains the ISBN for the song's album (if applicable).
LC - Contains the label code for the song's album.
MD5 - Contains the MD5 for the given file.
MusicBrainz Album Id - Contains the MusicBrainz Album UUID for the song's album. (MusicBrainz)
MusicBrainz Album Artist Id - Contains the MusicBrainz Artist UUID for the song's artist if it is from a "Various Artists" album. (MusicBrainz)
MusicBrainz Artist Id - Contains the MusicBrainz Artist UUID for the song's artist. (MusicBrainz)
MusicBrainz CDIndex - Contains the MusicBrainz CDIndex for the song's album (if lacking an MCDI tag).
MusicBrainz TRM Id - Contains the MusicBrainz TRM UUID for the song. (MusicBrainz)
http://musicbrainz.org - Contains the MusicBrainz Track UUID for the song. (MusicBrainz)
http://www.id3.org/dummy/ufid.html - A dummy link for UFID tag tests. (ID3v2.3)
Creative Commons - Contains a link to the Creative Commons Metadata for the file. (unofficial)
Tipster - Contains a link to the Tipster page for the file. (unofficial)