A symbol for 1000 circular mils, a unit of area equal to about 0.5067 square millimeter commonly used in stating wire gauges. This symbol is being replaced by the less-confusing symbol kcmil
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}