Symbol for the milligon (milligrad), a unit of angle measure equal to 0.001 gon, 10-5 right angle, 0.0009, 3.24 seconds of arc, or 15.708 microradians (rad). Surveying equipment is often marked in "mgons."
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}