It's called the New improved improved cinched knot. Yes you are right, that is 2 improved's and not a typo or double vision. You double the line and send it through and then back through a second time then make 3 0r 4 wrap arounds of the main line. After that you send the double short tag ends back down through the 2 loops that were form when you sent the taged in through eye. After that you can pull tight or you can take the taged ends back up through the loop that was formed when you did the previous step and pull tight forming the strongest knot known to man. You must be careful not to trim the wrong line or you will have to start all over. I do that often.