We'll keep it simple then. 1mil = 3.6" per 100yd.
MIL/MRAD and radians have nothing to do with centimeters and meters, it's an angle measurement, just like degrees.
There are 2*pi radians in a circle, and there are 1000 MIL (milliradians) in one radian.
MOA (minute of angle) is just 1/60th of a degree.
For example, a 10deg angle is 600 MOA
The same 10deg angle is .175 radians, or 175 MIL