Looking at the Keyboard Layout in CentOS 7.2, there are a 3rd and 4th characters for many keys. E.g., for 'd' there are the division sign and the degree symbol. I've tried the obvious key combinations-- Alt-d, Alt-Shift-d, etc.-- but no luck. Is there some configuration change I need to make in Gnome...? or what do I need to do to access these 3rd and 4th key characters?

tia