This Technical Memorandum defines a classification system for outdoor luminaires that provides information to lighting professionals regarding the lumen distribution within solid angles of specific interest. The lumens in the zones defined by this system are intended to be one of the metrics used to evaluate luminaire optical distribution and the potential for light pollution and obtrusive light, but not the only metric that should be evaluated.  Light pollution and obtrusive light result not only from the optical characteristics of luminaires, but also from the application of those luminaires within an outdoor site or roadway.  A detailed evaluation of the lighting performance for the outdoor site should be based not only on the luminaire optics, but also on the overall system design, including luminaire locations, utilization of light where it is needed, lighting quality, visual tasks, aesthetics, safety requirements, and security issues.