I'm not the OP, but what I think he is requesting is:
playlist A may contain filenames of music to play, and/or it may contain name of another playlist (B) to open and play. possibly playlist B could contain name of playlist C to open and play.
I've often wished for this when putting things that have multiple groups of files (large music compositions, a series of audiobooks). E.g., each audiobook would have its own playlist, each of which could be played individually, or a playlist for the whole series, which just invokes each individual book's playlist to make it easy to hear the whole series.