OKLab intends to offer a gamut of all screen-renderable colors.
There are three paramters: Light, a and b.
Light determines the middlest color of the a- and b-axis.
The a- and b-axis both hold two more or less complementairy colors at a negative to positve scale. Negative values for a and b represent cold colors and positive value represent warm colors.
Thus the light parameter takes on the hue and saturation of a color too.