Originally Posted by Maui19
Racquets strung with other strings may or may not vary this much from the target tension.
It is a mistake to think of it as "target tension". It isn't a target. As Rich S stated, it is known as reference tension and it's simply the number you set the machine at to get the feel you are looking for. That feel you are looking for is the target and yes it is lower than the reference tension.
An analogy perhaps would be shooting an arrow. If you are trying to hit the bulls eye and you find that you have to aim 3 ft above the bulls eye to hit it, that doesn't mean 3 ft above the bulls eye is your target. It's your reference point for finding the target.