Output – Specifies how the two colors are blended. See the examples below. Position along strand – Blends between Color A and Color B based on the relative position of the shaded point along a hair strand. The Color A parameter is used at the root of the strands, and the Color B parameter is used at the tip.
Random by strand index – Blends between Color A and Color B randomly based on the index of each strand.
Hair&Fur /Alembic color – Provides mapped hair color that is available from the geometry itself. This mode works with the color channel of alembic hair when used in its assigned material. It can also collect the material parameters information of the Hair&Fur (WSM) modifier. For the last, you need to set the mr prim mode in Hair and Fur Rendering options and apply the actual material in the Custom Shader rollout of the Hair&Fur parameters.
Hair&Fur opacity – This mode works only for Hair&Fur (WSM) modifier; the resulting color is taken from the opacity generated by the Tip Fade parameter of the Hair&Fur modifier.
Position along strand absolute – Blends between Color A and Color B based on the absolute distance of the shaded point along a hair strand. This option uses the Distance parameter instead of hair tip to pin the Color B position. When the Distance is lower than the actual hair length, the gradient is repeated over the length of the hair strand.
Position across strand – Blends between Color A and Color B based on the relative position of the shaded point across a hair strand. Color A – The first color used when Output is Position along strand, Position along strand absolute, or Random by strand index. This parameter can be mapped in the Maps section below. Color B – The second color used when Output is Position along strand, Position along strand absolute, or Random by strand index. This parameter can be mapped in the Maps section below. Bias – Can be used to move the middle point between the two colors when Output is Position along strand, Position along strand absolute, or Random by strand index. This parameter can be mapped in the Maps section below. Distance – Sets the max strand length when using Position along strand absolute. Typically, this value should be equal to the longest strand of hair. This option is mappable, allowing different parts in a hair system to have different max lengths. Seed offset – The random seed when Output is Random by strand index. | 
