The following is posted in the Wiki for the Pro-97:
Pro-97 - The RadioReference Wiki
Tips and Tricks
Tip not related in the User Guide: Press and hold the light background button until hear a "beep" sound. The light will be illuminated automatically on each transmission received.
This is not true, the back light is constantly illuminated once you hear a beep. This is misleading to some and would make you think that it functions like the Pro-528 does.
I just wanted to bring this to your attention.
Thanks