Cutoff, Semi (Lighting) : A luminary light distribution with 5% candela at an angle of 90 degrees or above and not more than 20% of emitted light above 80 degrees
Young & Company Electric Power Products and Related Engineering Services, Glossary of Electrical Terms, http://www.youngco.com/young2.asp?ID=4&Type=3, CA., USA 2001. (Electr Sfty - Amer) {514}