For example in the first row and second column, Stockfish vs Houdini, the result is 27-25+7-3=-16. I understand that 27 signifies Stockfish's number of wins+ draws, similarly 25 signifies that of Houdini. But what does "7-3" signify? and how is the result -16?
And what does the blank in Row 1, column 7 mean? similarly in (6,11), (7,1), (7,10), (7, 12), (10,7), (11,6), (11, 12), (12,7), (12,11). Do they signify that those matchups have never happened? If so Where should I look for if I want comparison of such matchups?
This question may be weird, but please at least guide me where should I ask these questions if not the answer.