I've buyed an old Bundeswehr milsurp 8x30 Hensoldt OD rubbered bino_ inside the right ocular I can see some kind of range-finding reticle, numbered from 0 to 40 on both sides_I know nothing about that, of course_ someone can explain me how use this reticle, even if unlikely I will be in need to call an arty support , or where to find some reference to learn something about that?_ any info will be welcomed!