sj_multi_mat is a standard diffuse/specular shader, but outputting a separate color for each of the lights in the Light List array.
So, there are 23 output colors: one for each of the ten allowed lights diffuse/specular contribution, one for the sum of all the diffuse contributions, one for the sum of all specular contributions, and one for the overall sum.
For each of the lights you can define the diffuse (Lambert, Ore N.W.) and specular (Phong, Blinn, Blong, Cook Torrance, Ward) model.
The order you define them, is based on the order in Light List.

A possible usage is shown here, where each of the components for the 3 lights, plus their sums, are sent to several channel storers.
Enjoy.