Color model

     set palette model { RGB | CMY | HSV {start <radians>} }

Sometimes RGB color space is not the most convenient color space to work in. You may change the color space model to one of RGB, HSV, CMY. RGB stands for Red, Green, Blue; CMY stands for Cyan, Magenta, Yellow; HSV stands for Hue, Saturation, Value. In HSV space the full color wheel is traversed as H runs from 0 to 1, so H=0 and H=1 describe the same color. By default the cycle starts and ends at red. The optional parameter start introduces an offset, so after set palette model HSV start 0.3 H=0 and H=1 both correspond to green.

For more information on color models see: http://en.wikipedia.org/wiki/Color_space

Documentation for palette options was written for RGB color space, so please note that R really means "first color component", which can be H or C depending on the actual color space in use.