Pontiac G3 2009 Owner's Manual page 168

An MP3/WMA CD that was recorded using no file
folders can also be played. The system can support up
to eight folders in depth, though, keep the depth of
the folders to a minimum in order to keep down
the complexity and confusion in trying to locate a
particular folder during playback. If a CD contains more
than the maximum of 50 folders, five sessions, and
999 files, the player lets you access and navigate up to
the maximum, but all items over the maximum are
ignored.
Root Directory
The root directory is treated as a folder. If the root
directory has compressed audio files, the directory is
displayed as ROOT. All files contained directly under the
root directory are accessed prior to any other directory.
Empty Directory or Folder
If a root directory or a folder exists somewhere in the
file structure that contains only folders/subfolders and
no compressed files directly beneath them, the player
advances to the next folder in the file structure that
contains compressed audio files. The empty folder
does not display.
3-52
No Folder
When a CD contains only compressed files, the files are
located under the root folder. The next and previous
folder function does not function on a CD that was
recorded without folders or playlists. When displaying
the name of the folder the radio displays ROOT.
When a CD contains only compressed audio files, but
no folders, all files are located under the root folder.
When the radio displays the name of the folder, the radio
displays ROOT.
Order of Play
The player play will begin from the first track under the
root directory. When all tracks from the root directory
have been played, play will continue from files according
to their numerical listing. After playing the last track
from the last folder, the player will begin playing again
at the first track of the first folder or root directory.
File System and Naming
The song name in the ID3 tag is displayed. If the song
name is not present in the ID3 tag, then the radio
displays the file name without the extension (such as
MP3/WMA) instead.
Track names longer than 32 characters or four pages
are shortened. Parts of words on the last page of
text and the extension of the filename does not display.