I do not quite understand how diplomatic relations work. Here is an example from my current game with Drath.
On this screenshot you can see that my current relations with Drath is 0 and if i want to create an alliance with them i need it to be at 9. By the way it is the only way i found to check current relations. I think it should be one of the first things you see on diplomatic screen.
And on this screenshot we see the summary of our relations which equals -3 (5 positive points and 8 negative).
So, which one is true, 0 or -3 ? Or is it that relations can't be less than zero ? But i checked other civs, and numbers don't add up with them too. For example, Manti relations should be 6, but tooltip says it's 5. So, what's the meaning of this ?