my reasoning: the actual colors we can see -> the wavelengths that we can extrapolate to -> basically extrapolated wavelengths plus an 'unpure-ness' factor -> not even real wavelengths (ok well king blue and maybe lavender if I'm being generous could be)
I guess the hue and maybe saturation are undefined there according to most color models (HSL would have hue and saturation undefined for white but HSV would only have hue undefined)