DVD spec details
 IFO files contain the map of the main menu, each title
 Primary source of information

 Streams broken into navigation segments:

 Title Sets contain logical groupings of video

 Program Chains (PGCs), independent video segments

 PGCs split into 'Cells', contain lists of small VOBUs

 Each VOBU has a navigation packet (NAV) for local context
 Navigation packets critical for playback
 Root source of difficulty for menuless players