The author is talking about a Bosch alternator with a built in voltage regulator. While this may be true for the Bosch it is not true for external voltage regulators found on most high output marine alternators.

You have three, and possibly four connections on an alternator: 1) ground 2) power output (B+) 3) field and possibly 4) tachometer output. The voltage regulator monitors the difference between ground and power output and applies power to the field at a level to get the power output voltage to the correct level based on it's charging algorithm.

That's all there is - there ain't no more.