To represent concepts and properties for describing music that can be found in personal music players. Music Group Group of musicians, or musical ensemble, usually popular or folk, playing parts of or improvising off of a musical arrangement. Playlist Slot A slot of a playlist. Musical Collection Any Musical Collection. Music Artist A music artist is a musician and/or singer who records and releases music. Musical Work Distinct intellectual or artistic musical creation. Song A short musical composition with words. Playlist A playlist of 'Musical work'. Album One or more recordings issued together. Discography A descriptive catalog of musical recordings recordered by an author. Genre An expressive style of music. has music video It associates the song with the video file encoding the video produced for the promoting the song or for artistic purposes. has slot It associates a 'Playlist' with the PlaylistSlots composing it. has genre It associates something (e.g. a Playlist, a Song) with the genre to which it belongs to. is recorded in It associates a MusicalWork with the AudioFile in whith it is recorded in. has first slot The first slot of the playlist. has author The creator of the musical work. has musical work A relation between a 'MusicalWork' and another entity which could be a container (i.e. Playlist) or an event (i.e. the user is listening to a certain song). has song A relation between a 'Song' and another entity which could be a container (i.e. Playlist) or an event (i.e. the user is listening to a certain song). directly follows directly precedes index It encodes the index of a 'PlaylistSlot'.