In Blender Cycles, in Shader nodes, the MixRGB node has an option "Clamp" that says: "Clamp result of the node to the 0..1 range". I can't think of a scenario where the node would output a result that's outside of this range. There's already a factor slider to mix the two color inputs, and for each color input, the slider options are already clamped between 0 and 1.
What is a scenario of when the MixRGB node would output a result that's outside the 0-1 range (and therefore is a case where "Clamp" can be useful)?