When I am using the radio, and I press and hold down the RDS button for a few seconds, the display shows REG OFF, then goes away. Likewise, if I hold down the RDS button again, REG ON is displayed.

I don't notice any changes. I asked my salesman today, he didn't know.

Does anyone know?

RDS is a function that very few stations support. You should also see a PTY button. I may have them crossed up, but if you tune into your public radio station (NPR) and hit the button to turn it on, RDS should display "PUBLIC" where the frequency would read out. PTY will then display "PUBLIC", right after the first one.

If you are able to find another station that does this it will read something like this:

Station in Chicago Magic 104.3
RDS: WJMK
PTY: OLDIES

Hope this helps.

I think I have the RDS and PTY down pat. To turn the RDS on and off, just touch the button. The * appears when it is on, and disappears when it is off.

This is different than RDS, even though it uses the same button. When holding down the RDS for a few seconds, does your display also read out "REG ON/OFF"? It completely displaces the current radio station on the display for a few seconds. You cannot miss it.

Hm, I don't get REG ON/OFF :dunno