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