misss_fast_shader is the workhorse shader that does the actual scattering. It is highly modular and works with several plug-in shaders, and it can even be cascaded into itself for multi-layer scattering (as is done in misss_fast_skin_maya where 3 layers of scattering are setup). It layers the results from the plug-in shaders with the scattered light from the lightmap (optionally nonlinearly, in what is known as “screen” transfer mode in various compositing applications) and presents the result as a final shaded ray.

misss_fast_lightmap_write is the lightmapping shader. Using it is required for the fast subsurface scattering to work. It creates a lightmap and stores the front and back surfaces, their depth, and irradiant light intensities in one or more specially formatted lightmaps.

misss_lambert_gamma is the supplied lightmap sampling shader. Any illumination shader can be used (e.g. mib illum lambert from the base library) but this one is specially tuned for the job and has options for lightmap gamma, normal flipping and indirect light inclusion.

misss_skin_specular is a function geared towards recreating the peculiar specular characteristics of skin. It contains dual specular highlights with edge enhancements plus glossy reflections. The shader can be used anywhere one wants a specular highlight, however, keep in mind it has no diffuse component, so it needs to be layered together (for example in a shader list or using mib_color_mix) with another shader to provide a diffuse component. Any other specularity shader can be used with misss_fast_shader (mib_illum_phong, mib_illum_ward...), as long as its diffuse is set to 0,0,0

misss_call_shader is a passthrough shader to call another shader useful for phenomena design. If you want to write an utility material phenomena, but you want the user of your phenomena to be able to specify his own environment shader, photon shader, etc. you need to call that shader trough this utility shader.

Unrelated to SSS, the following are extra shaders for occlusion effects and bump:

misss_simple_occlusion is a simple implementation of occlusion mapping which handles both reflective and ambient occlusion. "Occlusion" is the extent to which the area above a point is covered by other geometry. This is achieved by tracing a number of probe rays inside the hemispherical area above the point and testing to what extent this region is blocked. This shader works well when plugged into an ambient parameter like that of misss_fast_skin_maya. This shader can also be used outside of the SSS contest wherever ambient/reflective occlusion is needed.

misss_set_normal accepts a vector and sets the normal to this value, as maya wants it. So you can use misss_set_normal in the "bump" slot of the misss_fast_shader and connect whatever you normally connect to a maya bumpmap (usually outAlpha) to this shader. In the Maya phenomena it is exposed as "normalCamera" so you can connect standard maya bumpmaps directly as you would any other material that has a 'normalCamera' parameter.