Ok ... I think I'm getting the picture now. So to get this working you have to:

1. Note the order of the playlist entries in the database file, and their length tags.
2. If you want to find what fids are children of a given playlist (X), you sum up all the lengths of playlists (1) to (X) to make an offset (Y).
3. You open up the playlists file, go to offset (Y), and read in (length of playlist X) fids.

I guess the main assumption I'm making is that fid lists in the playlist file appear in the same order as their parent fids in the database file. Does this pseudo-code sound right?

Greg