HLS Files are now known to be a Hitlist Playlist. Hitlists group XA sounds together and are used in conjunction with TRK definitions and Logic Objects in the game. IE they control the files and the other filetypes control the variables.
WORD (1) - major version WORD (0) - minor version DWORD - Track Count
--Repeating DWORD - Instance IID for an XA or TRK file in the archive