New DJ Mix Flag.

To indicate that a track or album is a DJ Mix, we've added a new value  <flag> tag. When used at the album level, iTunes appends (DJ Mix) to the album version title. 

When used at track level, iTunes appends [Mixed] to the end of the track title. As a reminder, you can use <flag> to identify Remixes, Compilations, and Live content. 

To learn more about these changes, see the Flags sections, Album Metadata and Track Metadata in the iTunes Package Music Specification.