Lateral color

Lateral Color Fringes top
There no color fringes anywhere on a LEICA M9.
Materials and Construction top ...

Using a single cell does not give you complete correction for certain aberrations especially distortion, coma, and lateral color, ...

Color fringing (lateral colors at the image borders) does leave a distinctive clue in the MTF, but you need to examine a series of MTF curves measured at different apertures to detect it.

Lateral chromatic aberration also known as Transverse chromatic aberration - variation in the magnification at the sides of a lens (this aberration type used to be termed "lateral color"), ...

See also: Sharp, Sharpness, Wide-angle lens, Color, Lenses