The very last step in creating a DVD compliant direcory structure.
Very nearly all DVD authoring processes end with the two commands:
dvdauthor -t -o my-dvd-directory -c 0;15:00,30:00,45:00 my-movie.mpg
dvdauthor -T -o my-dvd-directory
Or something similar.
dvdauthor is well documented HERE: http://dvdauthor.sourceforge.net/doc/index.html