Mass Optical Density (MOD) : The ratio of the optical density of smoke and the mass loss of the test specimen, multiplied by the volume of the test chamber and divided by the length of the light path
NFPA 270 Standard Test Method for Measurement of Smoke Obscuration Using a Conical Radiant Source in a Single Closed Chamber, 2002 ed. http://www.baibiao.net/picture/18123144995.pdf, (Std: Tst Meth for Meas of Smoke Obscuration Using a Conical Rad Source in a Single Closed Chamber - Amer) {282 NFC}