I've seen that history.go() method can have two types of parameter:
see:
http://www.w3schools.com/jsref/met_his_go.asp
But url does not working at all.
I use JavaScript console of browser to test this method but got no success.
I know that there are security issues, that you can't read history entries. You can just go back and forward.
So why this string parameter listed in all js references?