what does the dot under your username mean?

[PipeDreams]

i notice some people have black dots, some people have green, what do they mean exactly?

 

[Bob Smith]

Reputation. You can vote on peoples reputation, as long as they dont have a black dot (meaning that reputation is disabled for that person). For people with green dots, there is a little button under one of their posts where you can make your vote.

 

[JMB]

so

So does this apply to the one post or overall? What is the meaning of this? I have never seen anyone with any color dot other then green or black. Since you are a supermod BOB I tried it on your post. I gave you a disapproval to see what would happen. Do you know what? My dumbass did not notice that yours is black anyways so WTF did it matter? Could you please elaborate a little more please? Thanks bro.
Respects,
JMB