Numbers go from 0.2 to 0.8 other numbers will not validate and turn red. 0.5 is linear (flat curve). below 0.5 you need more stick movement for a response and above 0.5 you will need less movement of the sticks.
Strange, if i move the graph(from 0.2 to 0.8 max) the number will be immediately be red, even if i put it back on 0.4. No matter what.
If i click on the number, i see "040", and i must typ "0,50" to change it to 0.5 (mind the ",") the number is still red, but it's saved when i go out of the EXP menu and go back.
If i move the graph, it wont be saved.
Tested on my Nexus 5 and nvidia shield.