On the ab plane, the print process in the L*a*b* color space is viewed from above, i.e. from the direction of white, and the lightness axis L* is perpendicular to the red-green a* axis and the yellow-blue b* axis. The closer a color is to the edge of the diagram, the greater its chroma. The angle indicates the hue. Every color mixture can be defined uniquely and displayed in the L*a*b* color space.
The color circle and the colored corners of the diagram help you in your orientation on the ab plane.
The green circles mark the tolerance range in the process standard for each process color. This graph shows the size of the color space and the position of the process colors in relation to the tolerance range on the ab plane.
The values must be within this green area to meet the process standard.