Symbol for one million standard cubic feet per day, the customary unit for measuring the production and flow of natural gas. "Standard" means that the measurement is adjusted to standard temperature (60ºF or 15.6ºC) and pressure (1 atmosphere)
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}