That's the thing about learning material creation in Maya, especially when it concerns Mental Ray shaders. If you're unfamiliar, you might find yourself using nodes like the dgs material, and dielectric etc when those are legacy shaders. I suggest learning mia_material_x to start(the plain "mia_material" is also one of those legacy nodes) and the "passes" versions of the shaders are the same as the "x"s except they work with the render pass system. The attributes are pretty straight forward for the most part and the help files do a good job of explaining those that aren't.