Here's a description of all of the input buttons for this box:
Ka controls the intensity of the ambient color. Kd controls the intensity of the diffuse color. Ks controls the intensity of the specular color. rgh controls the size of the specular highlight. OP is the surface opacity. AMB is the ambient surface color. DIF is the diffuse surface color. HI is the specular highlight color. NN can be used to change the surface normal.
..and the outputs are:
OI the surface opacity resulting from the shading calculations. CI the surface color resulting from the shading calculations.
These output values are the color and opacity which are passed to the renderer at any given micropolygon.
There are three lighting functions, ambient, diffuse and specular. Each of these are multiplied by their respective colors and intensity values. The results are added together to produce the output color of the plastic shader (CI).