Shader item layers shade surfaces from direct and indirect light sources, as well as determining the surface visibility. Each new scene, by default, has a single Base Shader item that takes care of these actions, but you may want to add other shader items to the Shader Tree. Modifying a shader layer's effect is useful when composing multiple passes out of Modo for a external application (such as Photoshop, After Effects, Nuke, or Fusion). Changing the effect of any shader item limits the output to that type information when passed on to render the output. However, shader items are layers, and you can mask and blend them to create unique possibilities. Unless necessary, use Render Outputs instead of shader items.
Diffuse Shading: Limits the output of the shader exclusively to the diffuse shading of the scene.
Fog Shading: Limits the output of the shader exclusively to the fog shading of the scene.
Full Shading: Passes along all the results of the Shader Tree to the render outputs. This is the default settings for any shader item.
Luminous Shading: Limits the output of the shader exclusively to the luminous shading of the scene.
Reflection Shading: Limits the output of the shader exclusively to the reflection shading of the scene.
Specular Shading: Limits the output of the shader exclusively to the specular shading of the scene.
Subsurface Shading: Limits the output of the shader exclusively to the subsurface shading of the scene.
Transparent Shading: Limits the output of the shader exclusively to the transparent shading of the scene.