I have a "transit", a telescope on a tripod with precision angles, and a rod marked in feet/inches (metric would be better).
http://www.runyonrental.com/LEVEL-TRANSIT-WTRIPOD-amp-STICK.item(Mine is much older, no plastic.)
It does many things, and it does "
stadia".
A Greek stadion was 600 feet. This was often used to measure roads (road-builder's payment, army travels).
My transit's stadia marks are "100:1". If my 6-foot assistant's head and shoes just fit between the stadia marks in my transit's grid, he is 600 feet away.
In modern road-building we need sticks in the ground every 100 (curves) or 1,000 (straights) feet. Instead of finding a 6-foot assistant, I look at the marks on the rod my helper holds (actually I strap the rod to a tree). If the stadia marks cover 1 foot of the rod (say, 4'3" to 5'3") then I am 100 feet from the rod; 10 feet, then I am 1,000 feet from the rod.
It would be more precise to use a survey chain (a very fancy tape-measure). However in road-building, the road goes from end to end, and we just need a lot of roughly 100 or 1,000 foot intervals to place marker sticks for the bulldozers and pavement machines. We only need to stay very-near the intended route (not drift onto private property). Apparently stadia-marks in transits "can" give error of 1 in 400, which is better than bad chain-work (it is hard to hold a tape/chain *exactly* straight over long distances). Stadia-estimation is much faster than dragging a chain.
Of course when shooting you can't send a boy to the target with a calibrated rod. Your question is: what is the intended target-size for this scope? In military small-arms it would of course be the size of a human. But overall standing in the clear? Just chin-to-helmet peeking over a hill? And this V-grid seems to go by width, not height.
And the "drop" for a given target and a given grid will be very different for a 30-06 war-rifle or a hobby air-rifle. When I used to shoot over 100 feet, the 30-06 went right-on, the .22 dropped several inches.
If you are target-shooting: sand-bags, measured range, and a lot of shooting will tell you how much drop to expect for how the target looks against the V-grid. But of course in target-shooting you probably already know the range, and how much drop your gun gives at that range.