They signify Left and Right mouse buttons. These will probably be replaced by an icon to avoid confusion.

(Click that box with LMB for class abilities, RMB for skills).

Oh, ok. :)

So in any other game (literally, every game I've ever played), when you hover your mouse over a button and it says (R), it means, "press (R) on the keyboard instead of clicking here." Maybe you *could* give people the hotkeys through that interface instead? (as well as left/right mouse button clicks) So that display I showed with be "(mX)use class ability (a) use skill" and so on.

Added mouse button icons. Reformatting the message would probably be a good idea. (pic) Either like that or brake it up into 2-3 lines.

Oh, that looks nice! I think 2 lines would be good - the top for the left click line, with the bottom for the right click.

Fixed. Now the real hotkeys in combination with the mouse buttons is displayed.