So there is second focal plane scopes (sometimes called rear focal) and first focal scopes. All of the second focal, which include all those mentioned, work according to their BDC charts when they are at "maximum" magnification.
So if you have a scope that says you zero at 100 yards (with your 308 or 223) and the hash marks are then 100 yards apart (so 200, 300, 400 etc) they "mean" that you have to be at max magnification for that to be true/close.
However, many of the mfg's have software (plus there is private software, Strelock as an example, which I use myself) that will spit out "what range" each of the BDC hashmarks will equate to at a given magnification - So if they are 100 yards apart at 14X and consistently 100 yards between hashes, at 9X on the same scope you may see something like 100 yards (center of the reticle), 232 yds (first hash), 347 yards (second hash) etc (and I'm just picking numbers out of the air here, but similar to what I see when I run the scope through my software).
Now first focal scopes or FFP's will give you the same distance/drop between hash marks no matter what magnification you set it at. But these scopes are normally two, three or four times as expensive and they are not without their downside issues. With a (normal) real focal/second focal scope, the reticle stays the same size (when viewing it) no matter what magnification you select. With FFP scopes the reticle gets larger or smaller as you adjust the magnification and some shooters find that unsettling/don't like it at low/high magnification (because sometimes the reticle is "tiny" and other times it's "gigantic") etc.
So just as an example, while you might find a Burris Fullfield II on the shelf for say 300 bucks, the E1/Predator Quest will be in 400-500 range (both second focal) if you move up to the FFP Veracity from Burris, now you are looking at a 900-1000 dollar scope, depending on the magnification range. And that's a considerable "leap" in cost (and I'm only talking cost here, because the Veracity is easily twice the scope that an E1/PQ is - so not saying "not worth it", just that the price jump is significant).