Originally Posted by TejasTom
The 6400 was important. (Most military forces have adopted the French "millieme" system. This is an approximation of a milli-radian (6283 per circle), in which the compass dial is spaced into 6400 units or "mils" for additional precision when measuring angles, laying artillery, etc. The value to the military is that one angular mil subtends approximately one metre at a distance of one kilometer.)
Nice work...I knew it would be a bit of an obscure reference but was hoping the "mils" verbage on the picture would help.