Literature
Roan [RnRn/nRn]
(RnRn/nRn) Roan Roan mutes and lightens and desaturates the base color with a mixture of white hair, usually on the back and thighs and even up to the tail.
In its dominant form, roan may also affect almost the entire body, safe for the head, the legs and the tailtip.
Roan can, but does not have to have little corn spots disrupting the white fur.
Roan does not have to be a pure white BUT needs to be significantly brighter and significantly less saturated than the base coat. nRn - Single Copy Roan Left is the Minimum amount of roan if only one copy is present (nRn).
Right is the Maximum amount of roan if only one copy is present ...