It appears to be simply a ranging reticle system with a series of hashmarks that r supposed to range a 50cm. target @100, 200, 300, etc.- 600 meters. It is a series of lines in the right lower quadrant of the reticle, and u're supposed to bracket the 50 cm. tgt. (deer, i guess) between x-hair and each line, and simply read off the # of each line which is supposed to be multipied by 100, and that's the range. Nice for 50 cm. tgts. but for anything else u would need to recalibrate it once subtensions are known. Now, what u can do is simply apply a modified mil-ranging formula to use it (or any other reticle for that matter to range any size tgt. with any reticle subtension once the subtension is known)-- here's a link to an article that describes the "modified mil-ranging formula" or better yet let's just call it the "stadia-ranging formula" since it's not specific to the mil-dot.
Part C) Reticle Rangefinding, Sections 1 and 2
Although the ZRF is nice, i prefer a reticle that provides downrange reticle zeroing, and windage reference as well. The ZRF could be adapted for both, but it would be difficult.