About Centiradians
The centiradian, or centrad (crad), is the radian with the prefix centi- applied: one hundredth of a radian.
A centiradian is 0.01 radians, or about 0.573°, and at a distance of 1 meter it spans 1cm. It sits between the radian and the milliradian and has few uses of its own.
About USSR milliradians
The USSR mil was the angle unit of Soviet artillery. It is a rounded version of the milliradian, within a few percent of one thousandth of a radian.
Soviet artillery used the mil in its sights and for estimating range: a target of known width that covers a measured number of mils gives the distance.
Like the other mils it is a military convention rather than an SI unit – each army chose a convenient number of divisions for the circle, so check which mil a figure refers to.
There are 6,000 USSR milliradians to a full circle.