Can somebody post a tutorial or an explanation for the fields throughout the shader_model and shader_environment tags, including the new sections for Opensauce v4?

I'm woefully unfamiliar with shaders. I understand quite a bit regarding color change masks and detail functions and all of that, but the new opensauce parts regarding Specular maps and the like I'm unfamiliar with, and I could use a refresh on the stock sections as well. I've quickly searched for tutorials here on Halomaps but didn't find much of worth.