It doesn't rely on order of operations, at least in this example? "Tarzan" will match one character earlier than Tarzan as the sting is scanned, so it would be

It doesn't rely on order of operations, at least in this example? "Tarzan" will match one character earlier than Tarzan as the sting is scanned, so it would be discarded even if you flipped the order of the alternation. This isn't true of examples where the good and bad marches can start at the same character.