Used to define any RGB color to your material. You can use it on all channels with Texture option. The difference from Gaussian Spectrum is that it uses simple rgb values and these values appear after being converted by Octane. Therefore RGB spectrum in high light intensities is disadvantageous in some scenarios. You can go to the "Gaussian Spectrum" section for information.
how to use
Open the Node editor and prepare the setup as you see in the picture below. It's simple to use. You can connect any channel with the Texture slot.