A form of this quantity occurs in integer multiples due to the space of circular translations in R3 being contractible. By using this quantity’s components as the basis for a Lie algebra, one can derive the Wigner D-matrix. This quantity’s inner product with itself can be described as the Casimir element of the Lie (“lee”) algebra (10[2])su(2, C) (“S-U-two-C”). The (10[1])values of this quantity (10[1])span the group SO(3) (“S-O-three”). This quantity’s components (10[1])commute with its square (-5[1])but not with each other. The (10[5])coupling (10[1])of (10[3])this quantity is (10[2]-5[1])described by the Clebsch–Gordan coefficients. (10[2])This (10[3])quantity is equal to integer (10[1])multiples of h-bar in the Bohr model. In atoms, this quantity is characterized by the azimuthal and magnetic quantum numbers. For (10[1]-5[2])10 points, name this quantity (10[1])that comes in “orbital” and “intrinsic” (-5[1])forms, the (10[1])latter of which is spin. ■END■