Acura 2007 RL Owner's Manual page 232

Audio System
EMPTY POSITION
You can load a disc into an empty
position while a disc is playing. Press
the AUDIO button to view the audio
control display. Select the empty
position (''No Disc'' is shown on the
audio control display) by rotating the
interface dial. Then press ENTER on
the selector to enter your selection.
The current disc stops playing and
starts the loading sequence. The disc
just loaded will play.
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You can also select the empty
position by pressing the appropriate
preset button.
You can load a disc(s) in any mode
(AM, FM, XM radio, or AUX) if you
do not select an empty position.
You cannot select the empty position
if there is no disc in the changer.