Just bought PX 780 and do not understand the "R: Pop" that displays as default on second line of display (screen or window) under the (first line) tone group, such as Grand Piano, Studio. Can anyone explain this to me. The manual does in fact picture this screen or display, but I do not see an explanation. If R mean reverberation, that is not one of the manual listed settings (room, hall, etc.). Thanks! UPDATE: I have not seen replies, but anyway Casio replied to an email (good for them!), & answered the question (R is "rhythm).