Could you please help me that explain what the result of coreference resolution means?

[motefly]

I tried the tools and get the result like:
Barack Obama was born in Hawaii. He is the president. Obama was elected in 2008.
"coref": [[[["He", 1, 0, 0, 1], ["Barack Obama", 0, 1, 0, 2]], [["the president", 1, 3, 2, 4], ["Barack Obama", 0, 1, 0, 2]], [["Obama", 2, 0, 0, 1], ["Barack Obama", 0, 1, 0, 2]]]]
So could you please help that what it means? Especially what the indices in the list mean?
Thank you very much!