partial luminous flux, <of a light source>
luminous flux emitted within a specified cone angle,
Note 1 to entry: (
Note 2 to entry: The cone angle,
Note 3 to entry: The term "cone luminous flux" is also used in some applications with the same meaning.
Note 4 to entry: See also "useful luminous flux".
Note 5 to entry: The partial luminous flux is expressed in lumen (lm).