See <<base-altitude ratio>>

A measure of the energy of the gamma rays produced by a particular type of emitter; it is the gamma-ray dose rate in roentgens per hour at a distance of 1 centimeter from a source having a radioactive disintegration rate of 1 millicurie (3.7 × 10⁷ disintegrations per second).

In artillery ground fire, a factor to be applied to the actual range to a point in order to determine the range which must be fired to hit that point; it is the result of registration and the solution of a meteorological message, and is expressed as plus or minus so many yards per thousand units of actual range.