This light value represents one of 4 different light sources (0 - 3). This series of values represents the RGB color values for the diffused light. The first three numbers represent the RGB values respectively. The numbers are somewhere between 0.0000 and 1.0000. 0.0 0.0 0.0 represents black, while 1.0 1.0 1.0 represents White. The last number is always set to 1.0.
Entry Name: Light0_Diffuse, Light1_Diffuse, Light2_Diffuse, Light3_Diffuse
Entry Type: Character String that specifies the RGB color Intensities. The default value is 1.0000 1.0000 1.0000 1.0 (White).
Diffuse light comes from one direction, so it's brighter if it comes squarely down on a surface than if it barely glances off the surface. Once it hits a surface, however, it's scattered equally in all directions, so it appears equally bright, no matter where the eye is located. Any light coming from a particular position or direction probably has a diffuse component.