A data frame of class tcs consisting of the following columns:
u, s, m, l: the quantum catch data used to
 calculate the remaining variables. NOTE: even if visual system is of type V-VIS,
 the output column will be labeled u.
u.r, s.r, m.r, l.r: relative cone stimulation,
 for a given hue, as a function of saturation. See Stoddard & Prum (2008) for details.
x, y, z: cartesian coordinates for the points in the
 tetrahedral color space.
h.theta, h.phi: angles theta and phi, in radians, determining
 the hue of the color.
r.vec: the r vector (saturation, distance from the achromatic center).
r.max: the maximum r vector achievable for the color's hue.
r.achieved: the relative r distance from the achromatic center, in
 relation to the maximum distance achievable (r.vec/r.max).