The RendererClass is a MAXClass wrapper of the plug-in renderer superclass which was added in 3ds Max 4 so that a renderer instance can be worked with in MAXScript.
The property .classes provides an array of all installed RendererClass objects, which allows for example the procedural creation of renderer class instances, the checking for available renderers on the current system and so on.
The shipping RendererClass classes are:
Default_Scanline_Renderer : RendererClass
Mental_Ray_Renderer : RendererClass
Quicksilver_Hardware_Renderer : RendererClass
VUE_File_Renderer : RendererClass