Hummer H2 2009 Owner's Manual page 255

Once all songs from that album are played, the player
moves to the next album in alphabetic order on the CD-R
or CD-RW and begin playing MP3 files from that album.
To exit music navigator mode, press the pushbutton
below the Back label to return to normal MP3 playback.
BAND: Press this button to listen to the radio when a
CD is playing. The CD remains safely inside the radio for
future listening.
CD/AUX (CD/Auxiliary): Press this button to play a CD
when listening to the radio. The CD icon and a message
showing disc and/or track number displays when a CD
is in the player. Press this button again and the system
automatically searches for an auxiliary input device such
as a portable audio player. If a portable audio player is
not connected, "No Input Device Found" displays.
Using an MP3 (Radio with CD and
DVD Player)
MP3/WMA CD-R or CD-RW Disc
Compressed Audio or Mixed Mode Discs
The radio also plays discs that contain both
uncompressed CD audio (.CDA files) and MP3/WMA files
depending on which slot the disc is loaded into. By default
the radio reads only the uncompressed audio (.CDA) and
ignores the MP3/WMA files on the DVD deck. On the CD
deck, press the CAT (category) button to toggle between
compressed and uncompressed audio format, the default
being the uncompressed format (.CDA).
3-99