This is a difficult subject to discuss, if you have not used the mildot system, for what it was designed for, 1st is ranging target distance, this is an art unto itself, but it does work well, but homework and math are needed to use it effectively. 2nd, the mildot system can be used for holdover, the wind or leading a moving target, this is used for shots that need to be taken quickly ( generally ) at unknown distances, because the target is getting away, and is best used with a good spotter, unless your rifle has no recoil and you can see the dirt fly in your scope. As previously mentioned, the bar section of the reticle, between the dots is a milradian, milradian = 3.6 minutes of angle, the dot itself varies, but an inch is common, and must be included, SO, 1 milradian + 1 mildot, = 4.6 minutes of angle, but you can take away half the dot, if your shooting for the center of the dot, so it = 4.1moa. At 200 yards this means that the distance between the actual center of the reticle and the 2nd dot would = 8.2 moa, roughly 8".
I recommend you go to
http://www.shooterready.com/lrsdemohi.html and play with their demo game, not just to play, but take the reticle ( mildot ) and move it up and down on the targets presented at different distances, and just look at the relationship between moving between 1 dot to the next, aiming at the same target, and the center of the reticle.
Now here is a link to what all those dots, and lines equal and a short course in using them.
http://www.eabco.com/Reports/MildotRep01.htmA scope that will fulfill most of what you expect is the Horace sighting system, here is a link to that, knobs are not needed too often, but the scope is busy. Benny Coolie uses one, and likes it, and Benny can shoot
www.dtic.mil/ndia/2002infantry/cutshaw2.pdf