This Standards Publication contains definitions@ dimensions@ and tolerances for recessed luminaires designed to use fluorescent@ high-intensity discharge and incandescent light sources.Drawing examples show fluorescent lamps. However@ these drawings also apply to high intensity discharge@ compact fluorescent@ incandescent@ and other lamp sources.This standard does not apply to ??hard metric dimensioned?? products. However@ ??soft metric dimensions?? or direct metric conversions may be applied throughout this standard as one inch equals 25.4 millimeters.